[PATCH] D129224: [InstCombine] Fold strtoul and strtoull and avoid PR #56293

[Eli Friedman via Phabricator via llvm-commits]

efriedma added inline comments.


================
Comment at: llvm/lib/Transforms/Utils/SimplifyLibCalls.cpp:117
+      if (Str[0] == '0') {
+        if (toUpper((unsigned char)Str[1]) == 'X') {
+          Base = 16;
----------------
The standard requires that a "0x" prefix be followed by a hexadecimal digit.  Similarly, the standard requires that a "0" prefix be followed by an octal digit.  If there isn't an appropriate digit after, the subject sequence (the part that's actually parsed as a number) is just a decimal "0".  And the rest is treated as "unrecognized characters".

The standard allows a "0x" prefix if the base is explicitly specified to be 16.


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D129224/new/

https://reviews.llvm.org/D129224