[PATCH] D30123: [InstCombine] shrink truncated splat shuffle
Sanjay Patel via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Tue Mar 7 08:22:34 PST 2017
This revision was automatically updated to reflect the committed changes.
Closed by commit rL297155: [InstCombine] shrink truncated splat shuffle (authored by spatel).
Changed prior to commit:
https://reviews.llvm.org/D30123?vs=89025&id=90857#toc
Repository:
rL LLVM
https://reviews.llvm.org/D30123
Files:
llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp
llvm/trunk/test/Transforms/InstCombine/trunc.ll
Index: llvm/trunk/test/Transforms/InstCombine/trunc.ll
===================================================================
--- llvm/trunk/test/Transforms/InstCombine/trunc.ll
+++ llvm/trunk/test/Transforms/InstCombine/trunc.ll
@@ -478,28 +478,26 @@
ret <4 x i8> %trunc
}
-; FIXME:
; trunc (shuffle X, undef, SplatMask) --> shuffle (trunc X), undef, SplatMask
define <4 x i8> @wide_splat1(<4 x i32> %x) {
; CHECK-LABEL: @wide_splat1(
-; CHECK-NEXT: [[SHUF:%.*]] = shufflevector <4 x i32> %x, <4 x i32> undef, <4 x i32> <i32 2, i32 2, i32 2, i32 2>
-; CHECK-NEXT: [[TRUNC:%.*]] = trunc <4 x i32> [[SHUF]] to <4 x i8>
+; CHECK-NEXT: [[TMP1:%.*]] = trunc <4 x i32> %x to <4 x i8>
+; CHECK-NEXT: [[TRUNC:%.*]] = shufflevector <4 x i8> [[TMP1]], <4 x i8> undef, <4 x i32> <i32 2, i32 2, i32 2, i32 2>
; CHECK-NEXT: ret <4 x i8> [[TRUNC]]
;
%shuf = shufflevector <4 x i32> %x, <4 x i32> undef, <4 x i32> <i32 2, i32 2, i32 2, i32 2>
%trunc = trunc <4 x i32> %shuf to <4 x i8>
ret <4 x i8> %trunc
}
-; FIXME:
; Test weird types.
; trunc (shuffle X, undef, SplatMask) --> shuffle (trunc X), undef, SplatMask
define <3 x i31> @wide_splat2(<3 x i33> %x) {
; CHECK-LABEL: @wide_splat2(
-; CHECK-NEXT: [[SHUF:%.*]] = shufflevector <3 x i33> %x, <3 x i33> undef, <3 x i32> <i32 1, i32 1, i32 1>
-; CHECK-NEXT: [[TRUNC:%.*]] = trunc <3 x i33> [[SHUF]] to <3 x i31>
+; CHECK-NEXT: [[TMP1:%.*]] = trunc <3 x i33> %x to <3 x i31>
+; CHECK-NEXT: [[TRUNC:%.*]] = shufflevector <3 x i31> [[TMP1]], <3 x i31> undef, <3 x i32> <i32 1, i32 1, i32 1>
; CHECK-NEXT: ret <3 x i31> [[TRUNC]]
;
%shuf = shufflevector <3 x i33> %x, <3 x i33> undef, <3 x i32> <i32 1, i32 1, i32 1>
Index: llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp
===================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -463,6 +463,23 @@
return BinaryOperator::Create(LogicOp->getOpcode(), NarrowOp0, NarrowC);
}
+/// Try to narrow the width of a splat shuffle. This could be generalized to any
+/// shuffle with a constant operand, but we limit the transform to avoid
+/// creating a shuffle type that targets may not be able to lower effectively.
+static Instruction *shrinkSplatShuffle(TruncInst &Trunc,
+ InstCombiner::BuilderTy &Builder) {
+ auto *Shuf = dyn_cast<ShuffleVectorInst>(Trunc.getOperand(0));
+ if (Shuf && Shuf->hasOneUse() && isa<UndefValue>(Shuf->getOperand(1)) &&
+ Shuf->getMask()->getSplatValue()) {
+ // trunc (shuf X, Undef, SplatMask) --> shuf (trunc X), Undef, SplatMask
+ Constant *NarrowUndef = UndefValue::get(Trunc.getType());
+ Value *NarrowOp = Builder.CreateTrunc(Shuf->getOperand(0), Trunc.getType());
+ return new ShuffleVectorInst(NarrowOp, NarrowUndef, Shuf->getMask());
+ }
+
+ return nullptr;
+}
+
Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
if (Instruction *Result = commonCastTransforms(CI))
return Result;
@@ -554,6 +571,9 @@
if (Instruction *I = shrinkBitwiseLogic(CI))
return I;
+ if (Instruction *I = shrinkSplatShuffle(CI, *Builder))
+ return I;
+
if (Src->hasOneUse() && isa<IntegerType>(SrcTy) &&
shouldChangeType(SrcTy, DestTy)) {
// Transform "trunc (shl X, cst)" -> "shl (trunc X), cst" so long as the
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