Hi Hans, [cc. Richard as code owner]
I'd like to nominate this commit for 3.9. The actual code churn is tiny, and this fixes a problem noticed by and causing pain to the qemu project. Cheers, James On Tue, 16 Aug 2016 at 10:53 James Molloy via cfe-commits < cfe-commits@lists.llvm.org> wrote: > Author: jamesm > Date: Tue Aug 16 04:45:36 2016 > New Revision: 278786 > > URL: http://llvm.org/viewvc/llvm-project?rev=278786&view=rev > Log: > Left shifts of negative values are defined if -fwrapv is set > > This means we shouldn't emit ubsan detection code or warn. > Fixes PR25552. > > Added: > cfe/trunk/test/CodeGen/wrapv-lshr-sanitize.c > cfe/trunk/test/Sema/negative-shift-wrapv.c > Modified: > cfe/trunk/lib/CodeGen/CGExprScalar.cpp > cfe/trunk/lib/Sema/SemaExpr.cpp > > Modified: cfe/trunk/lib/CodeGen/CGExprScalar.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGExprScalar.cpp?rev=278786&r1=278785&r2=278786&view=diff > > ============================================================================== > --- cfe/trunk/lib/CodeGen/CGExprScalar.cpp (original) > +++ cfe/trunk/lib/CodeGen/CGExprScalar.cpp Tue Aug 16 04:45:36 2016 > @@ -2714,7 +2714,8 @@ Value *ScalarExprEmitter::EmitShl(const > RHS = Builder.CreateIntCast(RHS, Ops.LHS->getType(), false, > "sh_prom"); > > bool SanitizeBase = CGF.SanOpts.has(SanitizerKind::ShiftBase) && > - Ops.Ty->hasSignedIntegerRepresentation(); > + Ops.Ty->hasSignedIntegerRepresentation() && > + !CGF.getLangOpts().isSignedOverflowDefined(); > bool SanitizeExponent = CGF.SanOpts.has(SanitizerKind::ShiftExponent); > // OpenCL 6.3j: shift values are effectively % word size of LHS. > if (CGF.getLangOpts().OpenCL) > > Modified: cfe/trunk/lib/Sema/SemaExpr.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Sema/SemaExpr.cpp?rev=278786&r1=278785&r2=278786&view=diff > > ============================================================================== > --- cfe/trunk/lib/Sema/SemaExpr.cpp (original) > +++ cfe/trunk/lib/Sema/SemaExpr.cpp Tue Aug 16 04:45:36 2016 > @@ -8670,7 +8670,7 @@ static void DiagnoseBadShiftValues(Sema& > > // If LHS does not have a signed type and non-negative value > // then, the behavior is undefined. Warn about it. > - if (Left.isNegative()) { > + if (Left.isNegative() && !S.getLangOpts().isSignedOverflowDefined()) { > S.DiagRuntimeBehavior(Loc, LHS.get(), > S.PDiag(diag::warn_shift_lhs_negative) > << LHS.get()->getSourceRange()); > > Added: cfe/trunk/test/CodeGen/wrapv-lshr-sanitize.c > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/wrapv-lshr-sanitize.c?rev=278786&view=auto > > ============================================================================== > --- cfe/trunk/test/CodeGen/wrapv-lshr-sanitize.c (added) > +++ cfe/trunk/test/CodeGen/wrapv-lshr-sanitize.c Tue Aug 16 04:45:36 2016 > @@ -0,0 +1,12 @@ > +// RUN: %clang_cc1 -fsanitize=shift-base -emit-llvm %s -o - -triple > x86_64-linux-gnu -fwrapv | FileCheck %s > + > +// CHECK-LABEL: @lsh_overflow > +int lsh_overflow(int a, int b) { > + // CHECK-NOT: br > + // CHECK-NOT: call void @__ubsan_ > + // CHECK-NOT: call void @llvm.trap > + > + // CHECK: %[[RET:.*]] = shl i32 > + // CHECK-NEXT: ret i32 %[[RET]] > + return a << b; > +} > > Added: cfe/trunk/test/Sema/negative-shift-wrapv.c > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/negative-shift-wrapv.c?rev=278786&view=auto > > ============================================================================== > --- cfe/trunk/test/Sema/negative-shift-wrapv.c (added) > +++ cfe/trunk/test/Sema/negative-shift-wrapv.c Tue Aug 16 04:45:36 2016 > @@ -0,0 +1,9 @@ > +// RUN: %clang_cc1 -Wall -ffreestanding -fsyntax-only -fwrapv -verify %s > + > +int test() { > + int i; > + i = -1 << 1; // no-warning > + return i; > +} > + > +// expected-no-diagnostics > > > _______________________________________________ > cfe-commits mailing list > cfe-commits@lists.llvm.org > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits >
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