r345816 - [clang][CodeGen] ImplicitIntegerSignChangeSanitizer: actually ignore NOP casts.

[Roman Lebedev via cfe-commits]

Author: lebedevri
Date: Thu Nov  1 01:56:51 2018
New Revision: 345816

URL: http://llvm.org/viewvc/llvm-project?rev=345816&view=rev
Log:
[clang][CodeGen] ImplicitIntegerSignChangeSanitizer: actually ignore NOP casts.

I fully expected for that to be handled by the canonical type check,
but it clearly wasn't. Sadly, somehow it hide until now.

Reported by Eli Friedman.

Modified:
    cfe/trunk/lib/CodeGen/CGExprScalar.cpp
    cfe/trunk/test/CodeGen/catch-implicit-integer-sign-changes-true-negatives.c

Modified: cfe/trunk/lib/CodeGen/CGExprScalar.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprScalar.cpp?rev=345816&r1=345815&r2=345816&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGExprScalar.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGExprScalar.cpp Thu Nov  1 01:56:51 2018
@@ -1127,10 +1127,9 @@ void ScalarExprEmitter::EmitIntegerSignC
   // Now, we do not need to emit the check in *all* of the cases.
   // We can avoid emitting it in some obvious cases where it would have been
   // dropped by the opt passes (instcombine) always anyways.
-  // If it's a cast between the same type, just differently-sugared. no check.
-  QualType CanonSrcType = CGF.getContext().getCanonicalType(SrcType);
-  QualType CanonDstType = CGF.getContext().getCanonicalType(DstType);
-  if (CanonSrcType == CanonDstType)
+  // If it's a cast between effectively the same type, no check.
+  // NOTE: this is *not* equivalent to checking the canonical types.
+  if (SrcSigned == DstSigned && SrcBits == DstBits)
     return;
   // At least one of the values needs to have signed type.
   // If both are unsigned, then obviously, neither of them can be negative.

Modified: cfe/trunk/test/CodeGen/catch-implicit-integer-sign-changes-true-negatives.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/catch-implicit-integer-sign-changes-true-negatives.c?rev=345816&r1=345815&r2=345816&view=diff
==============================================================================
--- cfe/trunk/test/CodeGen/catch-implicit-integer-sign-changes-true-negatives.c (original)
+++ cfe/trunk/test/CodeGen/catch-implicit-integer-sign-changes-true-negatives.c Thu Nov  1 01:56:51 2018
@@ -138,3 +138,15 @@ uint32_t unsigned_int_to_uint32(unsigned
 uint32_t uint32_to_uint32(uint32_t src) {
   return src;
 }
+
+// "Transparent" Enum.
+// ========================================================================== //
+
+enum a { b = ~2147483647 };
+enum a c();
+void d(int);
+void e();
+void e() {
+  enum a f = c();
+  d(f);
+}