[cfe-commits] r154849 - in /cfe/trunk: lib/AST/ExprConstant.cpp test/Sema/const-eval.c
Eli Friedman
eli.friedman at gmail.com
Mon Apr 16 12:23:58 PDT 2012
Author: efriedma
Date: Mon Apr 16 14:23:57 2012
New Revision: 154849
URL: http://llvm.org/viewvc/llvm-project?rev=154849&view=rev
Log:
Per Richard's comments on r154794, add the checks necessary to handle constant-folding relational comparisons safely in case the user is using -fwrapv or equivalent.
Modified:
cfe/trunk/lib/AST/ExprConstant.cpp
cfe/trunk/test/Sema/const-eval.c
Modified: cfe/trunk/lib/AST/ExprConstant.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=154849&r1=154848&r2=154849&view=diff
==============================================================================
--- cfe/trunk/lib/AST/ExprConstant.cpp (original)
+++ cfe/trunk/lib/AST/ExprConstant.cpp Mon Apr 16 14:23:57 2012
@@ -5090,8 +5090,6 @@
// The comparison here must be unsigned, and performed with the same
// width as the pointer.
- // FIXME: Knowing the base is the same for the LHS and RHS isn't enough
- // for relational operators.
unsigned PtrSize = Info.Ctx.getTypeSize(LHSTy);
uint64_t CompareLHS = LHSOffset.getQuantity();
uint64_t CompareRHS = RHSOffset.getQuantity();
@@ -5100,6 +5098,19 @@
CompareLHS &= Mask;
CompareRHS &= Mask;
+ // If there is a base and this is a relational operator, we can only
+ // compare pointers within the object in question; otherwise, the result
+ // depends on where the object is located in memory.
+ if (!LHSValue.Base.isNull() && E->isRelationalOp()) {
+ QualType BaseTy = getType(LHSValue.Base);
+ if (BaseTy->isIncompleteType())
+ return Error(E);
+ CharUnits Size = Info.Ctx.getTypeSizeInChars(BaseTy);
+ uint64_t OffsetLimit = Size.getQuantity();
+ if (CompareLHS > OffsetLimit || CompareRHS > OffsetLimit)
+ return Error(E);
+ }
+
switch (E->getOpcode()) {
default: llvm_unreachable("missing comparison operator");
case BO_LT: return Success(CompareLHS < CompareRHS, E);
Modified: cfe/trunk/test/Sema/const-eval.c
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/const-eval.c?rev=154849&r1=154848&r2=154849&view=diff
==============================================================================
--- cfe/trunk/test/Sema/const-eval.c (original)
+++ cfe/trunk/test/Sema/const-eval.c Mon Apr 16 14:23:57 2012
@@ -125,3 +125,9 @@
// <rdar://problem/10962435>
EVAL_EXPR(45, ((char*)-1) + 1 == 0 ? 1 : -1)
EVAL_EXPR(46, ((char*)-1) + 1 < (char*) -1 ? 1 : -1)
+EVAL_EXPR(47, &x < &x + 1 ? 1 : -1)
+EVAL_EXPR(48, &x != &x - 1 ? 1 : -1)
+EVAL_EXPR(49, &x < &x - 100 ? 1 : -1) // expected-error {{must have a constant size}}
+
+extern struct Test50S Test50;
+EVAL_EXPR(50, &Test50 < (struct Test50S*)((unsigned)&Test50 + 10)) // expected-error {{must have a constant size}}
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