Author: Roman Lebedev Date: 2020-08-18T12:26:01+02:00 New Revision: 522eeb66edfb0d6c4656d3f7a3f635544def30db
URL: https://github.com/llvm/llvm-project/commit/522eeb66edfb0d6c4656d3f7a3f635544def30db DIFF: https://github.com/llvm/llvm-project/commit/522eeb66edfb0d6c4656d3f7a3f635544def30db.diff LOG: [InstCombine] Sanitize undef vector constant to 1 in X*(2^C) with X << C (PR47133) While x*undef is undef, shift-by-undef is poison, which we must avoid introducing. Also log2(iN undef) is *NOT* iN undef, because log2(iN undef) u< N. See https://bugs.llvm.org/show_bug.cgi?id=47133 (cherry picked from commit 12d93a27e7b78d58dd00817cb737f273d2dba8ae) Added: Modified: llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp llvm/test/Transforms/InstCombine/getelementptr.ll Removed: ################################################################################ diff --git a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp index c6233a68847d..2f1325e80d2f 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp @@ -216,7 +216,11 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) { if (match(&I, m_Mul(m_Value(NewOp), m_Constant(C1)))) { // Replace X*(2^C) with X << C, where C is either a scalar or a vector. - if (Constant *NewCst = getLogBase2(NewOp->getType(), C1)) { + // Note that we need to sanitize undef multipliers to 1, + // to avoid introducing poison. + Constant *SafeC1 = Constant::replaceUndefsWith( + C1, ConstantInt::get(C1->getType()->getScalarType(), 1)); + if (Constant *NewCst = getLogBase2(NewOp->getType(), SafeC1)) { BinaryOperator *Shl = BinaryOperator::CreateShl(NewOp, NewCst); if (I.hasNoUnsignedWrap()) diff --git a/llvm/test/Transforms/InstCombine/getelementptr.ll b/llvm/test/Transforms/InstCombine/getelementptr.ll index 0257725d12de..17362b088241 100644 --- a/llvm/test/Transforms/InstCombine/getelementptr.ll +++ b/llvm/test/Transforms/InstCombine/getelementptr.ll @@ -216,7 +216,7 @@ define <2 x i1> @test13_vector(<2 x i64> %X, <2 x %S*> %P) nounwind { define <2 x i1> @test13_vector2(i64 %X, <2 x %S*> %P) nounwind { ; CHECK-LABEL: @test13_vector2( ; CHECK-NEXT: [[DOTSPLATINSERT:%.*]] = insertelement <2 x i64> undef, i64 [[X:%.*]], i32 0 -; CHECK-NEXT: [[TMP1:%.*]] = shl <2 x i64> [[DOTSPLATINSERT]], <i64 2, i64 undef> +; CHECK-NEXT: [[TMP1:%.*]] = shl <2 x i64> [[DOTSPLATINSERT]], <i64 2, i64 0> ; CHECK-NEXT: [[TMP2:%.*]] = icmp eq <2 x i64> [[TMP1]], <i64 -4, i64 undef> ; CHECK-NEXT: [[C:%.*]] = shufflevector <2 x i1> [[TMP2]], <2 x i1> undef, <2 x i32> zeroinitializer ; CHECK-NEXT: ret <2 x i1> [[C]] @@ -231,7 +231,7 @@ define <2 x i1> @test13_vector2(i64 %X, <2 x %S*> %P) nounwind { define <2 x i1> @test13_vector3(i64 %X, <2 x %S*> %P) nounwind { ; CHECK-LABEL: @test13_vector3( ; CHECK-NEXT: [[DOTSPLATINSERT:%.*]] = insertelement <2 x i64> undef, i64 [[X:%.*]], i32 0 -; CHECK-NEXT: [[TMP1:%.*]] = shl <2 x i64> [[DOTSPLATINSERT]], <i64 2, i64 undef> +; CHECK-NEXT: [[TMP1:%.*]] = shl <2 x i64> [[DOTSPLATINSERT]], <i64 2, i64 0> ; CHECK-NEXT: [[TMP2:%.*]] = icmp eq <2 x i64> [[TMP1]], <i64 4, i64 undef> ; CHECK-NEXT: [[C:%.*]] = shufflevector <2 x i1> [[TMP2]], <2 x i1> undef, <2 x i32> zeroinitializer ; CHECK-NEXT: ret <2 x i1> [[C]] _______________________________________________ llvm-branch-commits mailing list llvm-branch-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
