Looks fine to me. (At one point we were deliberately not following GCC in making -fwrapv affect left shift, because it's a bit operation rather than an arithmetic one, but this is ultimately supposed to be a GCC-compatible flag so behaving as they do seems reasonable.)
On Tue, Aug 16, 2016 at 9:38 AM, Aaron Ballman <aa...@aaronballman.com> wrote: > I'm not Richard, but I agree with merging it into 3.9 nonetheless. :-) > > ~Aaron > > On Tue, Aug 16, 2016 at 12:30 PM, Hans Wennborg via cfe-commits > <cfe-commits@lists.llvm.org> wrote: > > 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 >
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