always check for null in 'index' instructions

6 files changed, 132 insertions, 95 deletions

diff --git a/313index-bounds-check.subx b/313index-bounds-check.subx
index de9642fd..4bc8e12e 100644
--- a/313index-bounds-check.subx
+++ b/313index-bounds-check.subx
@@ -58,5 +58,8 @@ __check-mu-array-bounds:overflow:
     }
     # never gets here
 
+__mu-abort-null-index-base-address:
+    (abort "null address in 'index'")
+
 __mu-abort-null-get-base-address:
     (abort "null address in 'get'")
diff --git a/linux/313index-bounds-check.subx b/linux/313index-bounds-check.subx
index 1d7384c1..377d5adb 100644
--- a/linux/313index-bounds-check.subx
+++ b/linux/313index-bounds-check.subx
@@ -85,6 +85,14 @@ __check-mu-array-bounds:overflow:
 #            # actually save the index addr in reg
 #            "8d/copy-address *(" rega "+" regi "<<" log2(size-of(T)) "+4) " reg "/r32"
 
+__mu-abort-null-index-base-address:
+    (write-buffered Stderr "null address in 'index'\n")
+    (flush Stderr)
+    # exit(1)
+    bb/copy-to-ebx 1/imm32
+    e8/call syscall_exit/disp32
+    # never gets here
+
 __mu-abort-null-get-base-address:
     (write-buffered Stderr "null address in 'get'\n")
     (flush Stderr)
diff --git a/linux/mu b/linux/mu
index 2b2b8476..74374bee 100755
--- a/linux/mu
+++ b/linux/mu
Binary files differdiff --git a/linux/mu.subx b/linux/mu.subx
index 4ccf4854..07ba75a8 100644
--- a/linux/mu.subx
+++ b/linux/mu.subx
@@ -6309,15 +6309,17 @@ test-convert-index-into-array:
     (check-next-stream-line-equal _test-output-stream "    ff 6/subop/push %ecx"                    "F - test-convert-index-into-array/8")
     (check-next-stream-line-equal _test-output-stream "    b9/copy-to-ecx 3/imm32"                  "F - test-convert-index-into-array/9")
     (check-next-stream-line-equal _test-output-stream "    (__check-mu-array-bounds %ecx 0x00000004 *eax \"foo\" \"arr\")"  "F - test-convert-index-into-array/10")
-    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + ecx<<0x00000002 + 4) 0x00000000/r32"  "F - test-convert-index-into-array/11")
-    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %ecx"                     "F - test-convert-index-into-array/12")
-    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-index-into-array/13")
-    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-index-into-array/14")
-    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-index-into-array/15")
-    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-index-into-array/16")
-    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-index-into-array/17")
-    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-index-into-array/18")
-    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-index-into-array/19")
+    (check-next-stream-line-equal _test-output-stream "    81 7/subop/compare %eax 0/imm32"  "F - test-convert-index-into-array/11")
+    (check-next-stream-line-equal _test-output-stream "    0f 84/jump-if-= __mu-abort-null-index-base-address/disp32"  "F - test-convert-index-into-array/12")
+    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + ecx<<0x00000002 + 4) 0x00000000/r32"  "F - test-convert-index-into-array/13")
+    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %ecx"                     "F - test-convert-index-into-array/14")
+    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-index-into-array/15")
+    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-index-into-array/16")
+    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-index-into-array/17")
+    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-index-into-array/18")
+    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-index-into-array/19")
+    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-index-into-array/20")
+    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-index-into-array/21")
     # . epilogue
     89/<- %esp 5/r32/ebp
     5d/pop-to-ebp
@@ -6359,15 +6361,17 @@ test-convert-index-into-array-of-bytes:
     (check-next-stream-line-equal _test-output-stream "    ff 6/subop/push %ecx"                    "F - test-convert-index-into-array-of-bytes/8")
     (check-next-stream-line-equal _test-output-stream "    b9/copy-to-ecx 3/imm32"                  "F - test-convert-index-into-array-of-bytes/9")
     (check-next-stream-line-equal _test-output-stream "    (__check-mu-array-bounds %ecx 0x00000001 *eax \"foo\" \"arr\")"  "F - test-convert-index-into-array-of-bytes/10")
-    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + ecx<<0x00000000 + 4) 0x00000000/r32"  "F - test-convert-index-into-array-of-bytes/11")
-    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %ecx"                     "F - test-convert-index-into-array-of-bytes/12")
-    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-index-into-array-of-bytes/13")
-    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-index-into-array-of-bytes/14")
-    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-index-into-array-of-bytes/15")
-    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-index-into-array-of-bytes/16")
-    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-index-into-array-of-bytes/17")
-    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-index-into-array-of-bytes/18")
-    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-index-into-array-of-bytes/19")
+    (check-next-stream-line-equal _test-output-stream "    81 7/subop/compare %eax 0/imm32"  "F - test-convert-index-into-array-of-bytes/11")
+    (check-next-stream-line-equal _test-output-stream "    0f 84/jump-if-= __mu-abort-null-index-base-address/disp32"  "F - test-convert-index-into-array-of-bytes/12")
+    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + ecx<<0x00000000 + 4) 0x00000000/r32"  "F - test-convert-index-into-array-of-bytes/13")
+    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %ecx"                     "F - test-convert-index-into-array-of-bytes/14")
+    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-index-into-array-of-bytes/15")
+    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-index-into-array-of-bytes/16")
+    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-index-into-array-of-bytes/17")
+    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-index-into-array-of-bytes/18")
+    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-index-into-array-of-bytes/19")
+    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-index-into-array-of-bytes/20")
+    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-index-into-array-of-bytes/21")
     # . epilogue
     89/<- %esp 5/r32/ebp
     5d/pop-to-ebp
@@ -6406,15 +6410,17 @@ test-convert-index-into-array-with-literal:
     (check-next-stream-line-equal _test-output-stream "    ff 6/subop/push %eax"                    "F - test-convert-index-into-array-with-literal/6")
     (check-next-stream-line-equal _test-output-stream "    b8/copy-to-eax 0/imm32"                  "F - test-convert-index-into-array-with-literal/7")
     (check-next-stream-line-equal _test-output-stream "    (__check-mu-array-bounds 2 0x00000004 *eax \"foo\" \"arr\")"  "F - test-convert-index-into-array-with-literal/8")
+    (check-next-stream-line-equal _test-output-stream "    81 7/subop/compare %eax 0/imm32"  "F - test-convert-index-into-array-with-literal/9")
+    (check-next-stream-line-equal _test-output-stream "    0f 84/jump-if-= __mu-abort-null-index-base-address/disp32"  "F - test-convert-index-into-array-with-literal/10")
                                                                                  # 2 * 4 bytes/elem + 4 bytes for size = offset 12
-    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + 0x0000000c) 0x00000000/r32"  "F - test-convert-index-into-array-with-literal/9")
-    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-index-into-array-with-literal/10")
-    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-index-into-array-with-literal/11")
-    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-index-into-array-with-literal/12")
-    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-index-into-array-with-literal/13")
-    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-index-into-array-with-literal/14")
-    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-index-into-array-with-literal/15")
-    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-index-into-array-with-literal/16")
+    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + 0x0000000c) 0x00000000/r32"  "F - test-convert-index-into-array-with-literal/11")
+    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-index-into-array-with-literal/12")
+    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-index-into-array-with-literal/13")
+    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-index-into-array-with-literal/14")
+    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-index-into-array-with-literal/15")
+    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-index-into-array-with-literal/16")
+    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-index-into-array-with-literal/17")
+    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-index-into-array-with-literal/18")
     # . epilogue
     89/<- %esp 5/r32/ebp
     5d/pop-to-ebp
@@ -6453,15 +6459,17 @@ test-convert-index-into-array-of-bytes-with-literal:
     (check-next-stream-line-equal _test-output-stream "    ff 6/subop/push %eax"                    "F - test-convert-index-into-array-of-bytes-with-literal/6")
     (check-next-stream-line-equal _test-output-stream "    b8/copy-to-eax 0/imm32"                  "F - test-convert-index-into-array-of-bytes-with-literal/7")
     (check-next-stream-line-equal _test-output-stream "    (__check-mu-array-bounds 2 0x00000001 *eax \"foo\" \"arr\")"  "F - test-convert-index-into-array-of-bytes-with-literal/8")
+    (check-next-stream-line-equal _test-output-stream "    81 7/subop/compare %eax 0/imm32"  "F - test-convert-index-into-array-of-bytes-with-literal/9")
+    (check-next-stream-line-equal _test-output-stream "    0f 84/jump-if-= __mu-abort-null-index-base-address/disp32"  "F - test-convert-index-into-array-of-bytes-with-literal/10")
                                                                                  # 2 * 1 byte/elem + 4 bytes for size = offset 6
-    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + 0x00000006) 0x00000000/r32"  "F - test-convert-index-into-array-of-bytes-with-literal/8")
-    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-index-into-array-of-bytes-with-literal/9")
-    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-index-into-array-of-bytes-with-literal/10")
-    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-index-into-array-of-bytes-with-literal/11")
-    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-index-into-array-of-bytes-with-literal/12")
-    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-index-into-array-of-bytes-with-literal/13")
-    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-index-into-array-of-bytes-with-literal/14")
-    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-index-into-array-of-bytes-with-literal/15")
+    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + 0x00000006) 0x00000000/r32"  "F - test-convert-index-into-array-of-bytes-with-literal/11")
+    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-index-into-array-of-bytes-with-literal/12")
+    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-index-into-array-of-bytes-with-literal/13")
+    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-index-into-array-of-bytes-with-literal/14")
+    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-index-into-array-of-bytes-with-literal/15")
+    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-index-into-array-of-bytes-with-literal/16")
+    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-index-into-array-of-bytes-with-literal/17")
+    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-index-into-array-of-bytes-with-literal/18")
     # . epilogue
     89/<- %esp 5/r32/ebp
     5d/pop-to-ebp
@@ -6669,15 +6677,17 @@ test-convert-index-into-array-using-offset:
     (check-next-stream-line-equal _test-output-stream "    b9/copy-to-ecx 3/imm32"                  "F - test-convert-index-into-array-using-offset/9")
     (check-next-stream-line-equal _test-output-stream "    69/multiply %ecx 0x00000004/imm32 0x00000001/r32"  "F - test-convert-index-into-array-using-offset/10")
     (check-next-stream-line-equal _test-output-stream "    (__check-mu-array-bounds %ecx 1 *eax \"foo\" \"arr\")"  "F - test-convert-index-into-array-using-offset/11")
-    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + ecx + 4) 0x00000000/r32"  "F - test-convert-index-into-array-using-offset/12")
-    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %ecx"                     "F - test-convert-index-into-array-using-offset/13")
-    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-index-into-array-using-offset/14")
-    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-index-into-array-using-offset/15")
-    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-index-into-array-using-offset/16")
-    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-index-into-array-using-offset/17")
-    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-index-into-array-using-offset/18")
-    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-index-into-array-using-offset/19")
-    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-index-into-array-using-offset/20")
+    (check-next-stream-line-equal _test-output-stream "    81 7/subop/compare %eax 0/imm32"  "F - test-convert-index-into-array-using-offset/12")
+    (check-next-stream-line-equal _test-output-stream "    0f 84/jump-if-= __mu-abort-null-index-base-address/disp32"  "F - test-convert-index-into-array-using-offset/13")
+    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + ecx + 4) 0x00000000/r32"  "F - test-convert-index-into-array-using-offset/15")
+    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %ecx"                     "F - test-convert-index-into-array-using-offset/16")
+    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-index-into-array-using-offset/17")
+    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-index-into-array-using-offset/18")
+    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-index-into-array-using-offset/19")
+    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-index-into-array-using-offset/20")
+    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-index-into-array-using-offset/21")
+    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-index-into-array-using-offset/22")
+    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-index-into-array-using-offset/23")
     # . epilogue
     89/<- %esp 5/r32/ebp
     5d/pop-to-ebp
@@ -6721,15 +6731,17 @@ test-convert-index-into-array-of-bytes-using-offset:
     (check-next-stream-line-equal _test-output-stream "    b9/copy-to-ecx 3/imm32"                  "F - test-convert-index-into-array-of-bytes-using-offset/9")
     (check-next-stream-line-equal _test-output-stream "    69/multiply %ecx 0x00000001/imm32 0x00000001/r32"  "F - test-convert-index-into-array-of-bytes-using-offset/10")
     (check-next-stream-line-equal _test-output-stream "    (__check-mu-array-bounds %ecx 1 *eax \"foo\" \"arr\")"  "F - test-convert-index-into-array-of-bytes-using-offset/11")
-    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + ecx + 4) 0x00000000/r32"  "F - test-convert-index-into-array-of-bytes-using-offset/12")
-    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %ecx"                     "F - test-convert-index-into-array-of-bytes-using-offset/13")
-    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-index-into-array-of-bytes-using-offset/14")
-    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-index-into-array-of-bytes-using-offset/15")
-    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-index-into-array-of-bytes-using-offset/16")
-    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-index-into-array-of-bytes-using-offset/17")
-    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-index-into-array-of-bytes-using-offset/18")
-    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-index-into-array-of-bytes-using-offset/19")
-    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-index-into-array-of-bytes-using-offset/20")
+    (check-next-stream-line-equal _test-output-stream "    81 7/subop/compare %eax 0/imm32"  "F - test-convert-index-into-array-of-bytes-using-offset/12")
+    (check-next-stream-line-equal _test-output-stream "    0f 84/jump-if-= __mu-abort-null-index-base-address/disp32"  "F - test-convert-index-into-array-of-bytes-using-offset/13")
+    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + ecx + 4) 0x00000000/r32"  "F - test-convert-index-into-array-of-bytes-using-offset/14")
+    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %ecx"                     "F - test-convert-index-into-array-of-bytes-using-offset/15")
+    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-index-into-array-of-bytes-using-offset/16")
+    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-index-into-array-of-bytes-using-offset/17")
+    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-index-into-array-of-bytes-using-offset/18")
+    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-index-into-array-of-bytes-using-offset/19")
+    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-index-into-array-of-bytes-using-offset/20")
+    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-index-into-array-of-bytes-using-offset/21")
+    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-index-into-array-of-bytes-using-offset/22")
     # . epilogue
     89/<- %esp 5/r32/ebp
     5d/pop-to-ebp
@@ -6773,16 +6785,18 @@ test-convert-index-into-array-using-offset-on-stack:
     (check-next-stream-line-equal _test-output-stream "    ff 6/subop/push %ecx"                    "F - test-convert-index-into-array-using-offset-on-stack/9")
     (check-next-stream-line-equal _test-output-stream "    69/multiply *(ebp+0xfffffff8) 0x00000004/imm32 0x00000001/r32"  "F - test-convert-index-into-array-using-offset-on-stack/10")
     (check-next-stream-line-equal _test-output-stream "    (__check-mu-array-bounds %ecx 1 *eax \"foo\" \"arr\")"  "F - test-convert-index-into-array-using-offset-on-stack/11")
-    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + ecx + 4) 0x00000000/r32"  "F - test-convert-index-into-array-using-offset-on-stack/12")
-    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %ecx"                     "F - test-convert-index-into-array-using-offset-on-stack/13")
-    (check-next-stream-line-equal _test-output-stream "    81 0/subop/add %esp 0x00000004/imm32"    "F - test-convert-index-into-array-using-offset-on-stack/14")
-    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-index-into-array-using-offset-on-stack/15")
-    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-index-into-array-using-offset-on-stack/16")
-    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-index-into-array-using-offset-on-stack/17")
-    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-index-into-array-using-offset-on-stack/18")
-    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-index-into-array-using-offset-on-stack/19")
-    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-index-into-array-using-offset-on-stack/20")
-    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-index-into-array-using-offset-on-stack/21")
+    (check-next-stream-line-equal _test-output-stream "    81 7/subop/compare %eax 0/imm32"  "F - test-convert-index-into-array-using-offset-on-stack/12")
+    (check-next-stream-line-equal _test-output-stream "    0f 84/jump-if-= __mu-abort-null-index-base-address/disp32"  "F - test-convert-index-into-array-using-offset-on-stack/13")
+    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + ecx + 4) 0x00000000/r32"  "F - test-convert-index-into-array-using-offset-on-stack/14")
+    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %ecx"                     "F - test-convert-index-into-array-using-offset-on-stack/15")
+    (check-next-stream-line-equal _test-output-stream "    81 0/subop/add %esp 0x00000004/imm32"    "F - test-convert-index-into-array-using-offset-on-stack/16")
+    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-index-into-array-using-offset-on-stack/17")
+    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-index-into-array-using-offset-on-stack/18")
+    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-index-into-array-using-offset-on-stack/19")
+    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-index-into-array-using-offset-on-stack/20")
+    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-index-into-array-using-offset-on-stack/21")
+    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-index-into-array-using-offset-on-stack/22")
+    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-index-into-array-using-offset-on-stack/23")
     # . epilogue
     89/<- %esp 5/r32/ebp
     5d/pop-to-ebp
@@ -6826,16 +6840,18 @@ test-convert-index-into-array-of-bytes-using-offset-on-stack:
     (check-next-stream-line-equal _test-output-stream "    ff 6/subop/push %ecx"                    "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/9")
     (check-next-stream-line-equal _test-output-stream "    69/multiply *(ebp+0xfffffff8) 0x00000001/imm32 0x00000001/r32"  "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/10")
     (check-next-stream-line-equal _test-output-stream "    (__check-mu-array-bounds %ecx 1 *eax \"foo\" \"arr\")"  "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/11")
-    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + ecx + 4) 0x00000000/r32"  "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/12")
-    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %ecx"                     "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/13")
-    (check-next-stream-line-equal _test-output-stream "    81 0/subop/add %esp 0x00000004/imm32"    "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/14")
-    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/15")
-    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/16")
-    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/17")
-    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/18")
-    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/19")
-    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/20")
-    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/21")
+    (check-next-stream-line-equal _test-output-stream "    81 7/subop/compare %eax 0/imm32"  "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/12")
+    (check-next-stream-line-equal _test-output-stream "    0f 84/jump-if-= __mu-abort-null-index-base-address/disp32"  "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/13")
+    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + ecx + 4) 0x00000000/r32"  "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/14")
+    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %ecx"                     "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/15")
+    (check-next-stream-line-equal _test-output-stream "    81 0/subop/add %esp 0x00000004/imm32"    "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/16")
+    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/17")
+    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/18")
+    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/19")
+    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/20")
+    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/21")
+    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/22")
+    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-index-into-array-of-bytes-using-offset-on-stack/23")
     # . epilogue
     89/<- %esp 5/r32/ebp
     5d/pop-to-ebp
@@ -10668,15 +10684,17 @@ test-convert-array-of-user-defined-types:
     (check-next-stream-line-equal _test-output-stream "    ff 6/subop/push %ecx"                    "F - test-convert-array-of-user-defined-types/8")
     (check-next-stream-line-equal _test-output-stream "    b9/copy-to-ecx 3/imm32"                  "F - test-convert-array-of-user-defined-types/9")
     (check-next-stream-line-equal _test-output-stream "    (__check-mu-array-bounds %ecx 0x00000008 *eax \"foo\" \"arr\")"  "F - test-convert-array-of-user-defined-types/10")
-    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + ecx<<0x00000003 + 4) 0x00000000/r32"  "F - test-convert-array-of-user-defined-types/11")
-    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %ecx"                     "F - test-convert-array-of-user-defined-types/12")
-    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-array-of-user-defined-types/13")
-    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-array-of-user-defined-types/14")
-    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-array-of-user-defined-types/15")
-    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-array-of-user-defined-types/16")
-    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-array-of-user-defined-types/17")
-    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-array-of-user-defined-types/18")
-    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-array-of-user-defined-types/19")
+    (check-next-stream-line-equal _test-output-stream "    81 7/subop/compare %eax 0/imm32"  "F - test-convert-array-of-user-defined-types/12")
+    (check-next-stream-line-equal _test-output-stream "    0f 84/jump-if-= __mu-abort-null-index-base-address/disp32"  "F - test-convert-array-of-user-defined-types/13")
+    (check-next-stream-line-equal _test-output-stream "    8d/copy-address *(eax + ecx<<0x00000003 + 4) 0x00000000/r32"  "F - test-convert-array-of-user-defined-types/14")
+    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %ecx"                     "F - test-convert-array-of-user-defined-types/15")
+    (check-next-stream-line-equal _test-output-stream "    8f 0/subop/pop %eax"                     "F - test-convert-array-of-user-defined-types/16")
+    (check-next-stream-line-equal _test-output-stream "  }"                                         "F - test-convert-array-of-user-defined-types/17")
+    (check-next-stream-line-equal _test-output-stream "$foo:0x00000001:break:"                      "F - test-convert-array-of-user-defined-types/18")
+    (check-next-stream-line-equal _test-output-stream "  # . epilogue"                              "F - test-convert-array-of-user-defined-types/19")
+    (check-next-stream-line-equal _test-output-stream "  89/<- %esp 5/r32/ebp"                      "F - test-convert-array-of-user-defined-types/20")
+    (check-next-stream-line-equal _test-output-stream "  5d/pop-to-ebp"                             "F - test-convert-array-of-user-defined-types/21")
+    (check-next-stream-line-equal _test-output-stream "  c3/return"                                 "F - test-convert-array-of-user-defined-types/22")
     # . epilogue
     89/<- %esp 5/r32/ebp
     5d/pop-to-ebp
@@ -29476,17 +29494,25 @@ translate-mu-index-stmt-with-array-in-register:  # out: (addr buffered-file), st
     51/push-ecx
     52/push-edx
     53/push-ebx
-    #
-    (emit-indent *(ebp+8) *Curr-block-depth)
-    (write-buffered *(ebp+8) "8d/copy-address *(")
-    # TODO: ensure inouts[0] is in a register and not dereferenced
-$translate-mu-index-stmt-with-array-in-register:emit-base:
     # ecx = stmt
     8b/-> *(ebp+0xc) 1/r32/ecx
     # var base/ebx: (addr var) = inouts[0]
     (lookup *(ecx+0xc) *(ecx+0x10))  # Stmt1-inouts Stmt1-inouts => eax
     (lookup *eax *(eax+4))  # Stmt-var-value Stmt-var-value => eax
     89/<- %ebx 0/r32/eax
+    # emit null check
+    (emit-indent *(ebp+8) *Curr-block-depth)
+    (write-buffered *(ebp+8) "81 7/subop/compare %")
+    (lookup *(ebx+0x18) *(ebx+0x1c))  # Var-register Var-register => eax
+    (write-buffered *(ebp+8) %eax)
+    (write-buffered *(ebp+8) " 0/imm32\n")
+    (emit-indent *(ebp+8) *Curr-block-depth)
+    (write-buffered *(ebp+8) "0f 84/jump-if-= __mu-abort-null-index-base-address/disp32\n")
+    #
+    (emit-indent *(ebp+8) *Curr-block-depth)
+    (write-buffered *(ebp+8) "8d/copy-address *(")
+    # TODO: ensure inouts[0] is in a register and not dereferenced
+$translate-mu-index-stmt-with-array-in-register:emit-base:
     # print base->register " + "
     (lookup *(ebx+0x18) *(ebx+0x1c))  # Var-register Var-register => eax
     (write-buffered *(ebp+8) %eax)
diff --git a/mu-init.subx b/mu-init.subx
index da22b2b3..c1c6b435 100644
--- a/mu-init.subx
+++ b/mu-init.subx
@@ -12,12 +12,6 @@
 Entry:
   # initialize stack
   bd/copy-to-ebp 0/imm32
-  # Clear memory location 0 to ensure that uninitialized arrays run afoul of
-  # the bounds checker.
-  # TODO: This is utterly bonkers, and does not actually protect us against
-  # all null pointer reads/writes. Create a real page table sometime.
-  b8/copy-to-eax 0/imm32
-  c7 0/subop/copy *eax 0/imm32
   #
 #?   (main 0 0 Primary-bus-secondary-drive)
   # always first run tests
diff --git a/mu_instructions b/mu_instructions
index ea58866e..10d00f10 100644
--- a/mu_instructions
+++ b/mu_instructions
@@ -318,13 +318,17 @@ var/reg: (addr T) <- address var2: T
 
 var/reg: (addr T) <- index arr/rega: (addr array T), idx/regi: int
   | if size-of(T) is 1, 2, 4 or 8
-      => "(__check-mu-array-bounds *" rega " %" regi " " size-of(T) ")"
+      => "81 7/subop/compare %" rega " 0/imm32"
+         "0f 84/jump-if-= __mu-abort-null-index-base-address/disp32"
+         "(__check-mu-array-bounds *" rega " %" regi " " size-of(T) ")"
          "8d/copy-address *(" rega "+" regi "<<" log2(size-of(T)) "+4) " reg "/r32"
 var/reg: (addr T) <- index arr: (array T len), idx/regi: int
   => "(__check-mu-array-bounds *(ebp+" arr.stack-offset ") %" regi " " size-of(T) ")"
      "8d/copy-address *(ebp+" regi "<<" log2(size-of(T)) "+" (arr.stack-offset + 4) ") " reg "/r32"
 var/reg: (addr T) <- index arr/rega: (addr array T), n
-  => "(__check-mu-array-bounds *" rega " " n " " size-of(T) ")"
+  => "81 7/subop/compare %" rega " 0/imm32"
+     "0f 84/jump-if-= __mu-abort-null-index-base-address/disp32"
+     "(__check-mu-array-bounds *" rega " " n " " size-of(T) ")"
      "8d/copy-address *(" rega "+" (n*size-of(T)+4) ") " reg "/r32"
 var/reg: (addr T) <- index arr: (array T len), n
   => "(__check-mu-array-bounds *(ebp+" arr.stack-offset ") " n " " size-of(T) ")"
@@ -335,7 +339,9 @@ var/reg: (offset T) <- compute-offset arr: (addr array T), idx/regi: int  # arr
 var/reg: (offset T) <- compute-offset arr: (addr array T), idx: int       # arr can be in reg or mem
   => "69/multiply *(ebp+" idx.stack-offset ") " size-of(T) "/imm32 " reg "/r32"
 var/reg: (addr T) <- index arr/rega: (addr array T), o/rego: (offset T)
-  => "(__check-mu-array-bounds %" rega " %" rego " 1 \"" function-name "\")"
+  => "81 7/subop/compare %" rega " 0/imm32"
+     "0f 84/jump-if-= __mu-abort-null-index-base-address/disp32"
+     "(__check-mu-array-bounds %" rega " %" rego " 1 \"" function-name "\")"
      "8d/copy-address *(" rega "+" rego "+4) " reg "/r32"
 
 Computing the length of an array is complex.