diff options
Diffstat (limited to 'llvm')
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstructionCombining.cpp | 16 | ||||
| -rw-r--r-- | llvm/test/Transforms/InstCombine/vec_shuffle.ll | 8 |
2 files changed, 20 insertions, 4 deletions
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp index 7ccb65d6531..7a34419bfe9 100644 --- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp +++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp @@ -1421,6 +1421,22 @@ Value *InstCombiner::SimplifyVectorOp(BinaryOperator &Inst) { } } if (MayChange) { + // It's not safe to use a vector with undef elements because the entire + // instruction can be folded to undef (for example, div/rem divisors). + // Replace undef lanes with the first non-undef element. Vector demanded + // elements can change those back to undef values if that is safe. + Constant *SafeDummyConstant = nullptr; + for (unsigned i = 0; i < VWidth; ++i) { + if (!isa<UndefValue>(NewVecC[i])) { + SafeDummyConstant = NewVecC[i]; + break; + } + } + assert(SafeDummyConstant && "Undef constant vector was not simplified?"); + for (unsigned i = 0; i < VWidth; ++i) + if (isa<UndefValue>(NewVecC[i])) + NewVecC[i] = SafeDummyConstant; + // Op(shuffle(V1, Mask), C) -> shuffle(Op(V1, NewC), Mask) // Op(C, shuffle(V1, Mask)) -> shuffle(Op(NewC, V1), Mask) Constant *NewC = ConstantVector::get(NewVecC); diff --git a/llvm/test/Transforms/InstCombine/vec_shuffle.ll b/llvm/test/Transforms/InstCombine/vec_shuffle.ll index 5447063bbf6..1b692496384 100644 --- a/llvm/test/Transforms/InstCombine/vec_shuffle.ll +++ b/llvm/test/Transforms/InstCombine/vec_shuffle.ll @@ -452,7 +452,7 @@ define <4 x i32> @mul_const_splat(<4 x i32> %v) { define <4 x i32> @lshr_const_half_splat(<4 x i32> %v) { ; CHECK-LABEL: @lshr_const_half_splat( -; CHECK-NEXT: [[TMP1:%.*]] = lshr <4 x i32> <i32 undef, i32 8, i32 9, i32 undef>, [[V:%.*]] +; CHECK-NEXT: [[TMP1:%.*]] = lshr <4 x i32> <i32 8, i32 8, i32 9, i32 8>, [[V:%.*]] ; CHECK-NEXT: [[TMP2:%.*]] = shufflevector <4 x i32> [[TMP1]], <4 x i32> undef, <4 x i32> <i32 1, i32 1, i32 2, i32 2> ; CHECK-NEXT: ret <4 x i32> [[TMP2]] ; @@ -583,11 +583,11 @@ define <2 x i32*> @pr23113(<4 x i32*> %A) { ret <2 x i32*> %1 } -; FIXME: Unused lanes in the new binop should not kill the entire op. +; Unused lanes in the new binop should not kill the entire op (although it may simplify anyway as shown here). define <2 x i32> @PR37648(<2 x i32> %x) { ; CHECK-LABEL: @PR37648( -; CHECK-NEXT: ret <2 x i32> undef +; CHECK-NEXT: ret <2 x i32> zeroinitializer ; %splat = shufflevector <2 x i32> %x, <2 x i32> undef, <2 x i32> zeroinitializer %r = urem <2 x i32> %splat, <i32 1, i32 1> @@ -596,7 +596,7 @@ define <2 x i32> @PR37648(<2 x i32> %x) { define <2 x float> @splat_first_fp(<2 x float> %x) { ; CHECK-LABEL: @splat_first_fp( -; CHECK-NEXT: [[TMP1:%.*]] = fadd <2 x float> [[X:%.*]], <float 1.000000e+00, float undef> +; CHECK-NEXT: [[TMP1:%.*]] = fadd <2 x float> [[X:%.*]], <float 1.000000e+00, float 1.000000e+00> ; CHECK-NEXT: [[TMP2:%.*]] = shufflevector <2 x float> [[TMP1]], <2 x float> undef, <2 x i32> zeroinitializer ; CHECK-NEXT: ret <2 x float> [[TMP2]] ; |
