Seems reasonable to me if Richard agrees.
On Tue, Aug 16, 2016 at 3:01 AM, James Molloy <ja...@jamesmolloy.co.uk> wrote: > 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 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
