[llvm] 464b9ae - [InstCombine] Transform extelt-trunc -> bitcast-extelt
Daan Sprenkels via llvm-commits
llvm-commits at lists.llvm.org
Tue Mar 31 02:55:31 PDT 2020
Author: Daan Sprenkels
Date: 2020-03-31T11:53:41+02:00
New Revision: 464b9aeafe29104a1a8391f43f91835eeca473b3
URL: https://github.com/llvm/llvm-project/commit/464b9aeafe29104a1a8391f43f91835eeca473b3
DIFF: https://github.com/llvm/llvm-project/commit/464b9aeafe29104a1a8391f43f91835eeca473b3.diff
LOG: [InstCombine] Transform extelt-trunc -> bitcast-extelt
Canonicalize the case when a scalar extracted from a vector is
truncated. Transform such cases to bitcast-then-extractelement.
This will enable erasing the truncate operation.
This commit fixes PR45314.
reviewers: spatel
Differential revision: https://reviews.llvm.org/D76983
Added:
Modified:
llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
llvm/test/Transforms/InstCombine/ExtractCast.ll
llvm/test/Transforms/InstCombine/trunc-extractelement.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
index afdddad10cea..58f9dcedb15f 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
@@ -690,6 +690,7 @@ Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
Value *Src = CI.getOperand(0);
Type *DestTy = CI.getType(), *SrcTy = Src->getType();
+ ConstantInt *Cst;
// Attempt to truncate the entire input expression tree to the destination
// type. Only do this if the dest type is a simple type, don't convert the
@@ -758,7 +759,7 @@ Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
// more efficiently. Support vector types. Cleanup code by using m_OneUse.
// Transform trunc(lshr (zext A), Cst) to eliminate one type conversion.
- Value *A = nullptr; ConstantInt *Cst = nullptr;
+ Value *A = nullptr;
if (Src->hasOneUse() &&
match(Src, m_LShr(m_ZExt(m_Value(A)), m_ConstantInt(Cst)))) {
// We have three types to worry about here, the type of A, the source of
@@ -843,6 +844,38 @@ Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
if (Instruction *I = foldVecTruncToExtElt(CI, *this))
return I;
+ // Whenever an element is extracted from a vector, and then truncated,
+ // canonicalize by converting it to a bitcast followed by an
+ // extractelement.
+ //
+ // Example (little endian):
+ // trunc (extractelement <4 x i64> %X, 0) to i32
+ // --->
+ // extractelement <8 x i32> (bitcast <4 x i64> %X to <8 x i32>), i32 0
+ Value *VecOp;
+ if (match(Src,
+ m_OneUse(m_ExtractElement(m_Value(VecOp), m_ConstantInt(Cst))))) {
+ Type *VecOpTy = VecOp->getType();
+ unsigned DestScalarSize = DestTy->getScalarSizeInBits();
+ unsigned VecOpScalarSize = VecOpTy->getScalarSizeInBits();
+ unsigned VecNumElts = VecOpTy->getVectorNumElements();
+
+ // A badly fit destination size would result in an invalid cast.
+ if (VecOpScalarSize % DestScalarSize == 0) {
+ uint64_t TruncRatio = VecOpScalarSize / DestScalarSize;
+ uint64_t BitCastNumElts = VecNumElts * TruncRatio;
+ uint64_t VecOpIdx = Cst->getZExtValue();
+ uint64_t NewIdx = DL.isBigEndian() ? (VecOpIdx + 1) * TruncRatio - 1
+ : VecOpIdx * TruncRatio;
+ assert(BitCastNumElts <= std::numeric_limits<uint32_t>::max() &&
+ "overflow 32-bits");
+
+ Type *BitCastTo = VectorType::get(DestTy, BitCastNumElts);
+ Value *BitCast = Builder.CreateBitCast(VecOp, BitCastTo);
+ return ExtractElementInst::Create(BitCast, Builder.getInt32(NewIdx));
+ }
+ }
+
return nullptr;
}
diff --git a/llvm/test/Transforms/InstCombine/ExtractCast.ll b/llvm/test/Transforms/InstCombine/ExtractCast.ll
index 91df10241d44..9dc9396837c2 100644
--- a/llvm/test/Transforms/InstCombine/ExtractCast.ll
+++ b/llvm/test/Transforms/InstCombine/ExtractCast.ll
@@ -3,8 +3,8 @@
define i32 @a(<4 x i64> %I) {
; CHECK-LABEL: @a(
-; CHECK-NEXT: [[TMP1:%.*]] = extractelement <4 x i64> [[I:%.*]], i32 3
-; CHECK-NEXT: [[K:%.*]] = trunc i64 [[TMP1]] to i32
+; CHECK-NEXT: [[TMP1:%.*]] = bitcast <4 x i64> [[I:%.*]] to <8 x i32>
+; CHECK-NEXT: [[K:%.*]] = extractelement <8 x i32> [[TMP1]], i32 6
; CHECK-NEXT: ret i32 [[K]]
;
%J = trunc <4 x i64> %I to <4 x i32>
diff --git a/llvm/test/Transforms/InstCombine/trunc-extractelement.ll b/llvm/test/Transforms/InstCombine/trunc-extractelement.ll
index 9f4ff5d9ce22..c44577d1f1d1 100644
--- a/llvm/test/Transforms/InstCombine/trunc-extractelement.ll
+++ b/llvm/test/Transforms/InstCombine/trunc-extractelement.ll
@@ -3,10 +3,15 @@
; RUN: opt < %s -instcombine -S -data-layout="E" | FileCheck %s --check-prefixes=ANY,BE
define i32 @shrinkExtractElt_i64_to_i32_0(<3 x i64> %x) {
-; ANY-LABEL: @shrinkExtractElt_i64_to_i32_0(
-; ANY-NEXT: [[E:%.*]] = extractelement <3 x i64> [[X:%.*]], i32 0
-; ANY-NEXT: [[T:%.*]] = trunc i64 [[E]] to i32
-; ANY-NEXT: ret i32 [[T]]
+; LE-LABEL: @shrinkExtractElt_i64_to_i32_0(
+; LE-NEXT: [[TMP1:%.*]] = bitcast <3 x i64> [[X:%.*]] to <6 x i32>
+; LE-NEXT: [[T:%.*]] = extractelement <6 x i32> [[TMP1]], i32 0
+; LE-NEXT: ret i32 [[T]]
+;
+; BE-LABEL: @shrinkExtractElt_i64_to_i32_0(
+; BE-NEXT: [[TMP1:%.*]] = bitcast <3 x i64> [[X:%.*]] to <6 x i32>
+; BE-NEXT: [[T:%.*]] = extractelement <6 x i32> [[TMP1]], i32 1
+; BE-NEXT: ret i32 [[T]]
;
%e = extractelement <3 x i64> %x, i32 0
%t = trunc i64 %e to i32
@@ -14,10 +19,15 @@ define i32 @shrinkExtractElt_i64_to_i32_0(<3 x i64> %x) {
}
define i32 @shrinkExtractElt_i64_to_i32_1(<3 x i64> %x) {
-; ANY-LABEL: @shrinkExtractElt_i64_to_i32_1(
-; ANY-NEXT: [[E:%.*]] = extractelement <3 x i64> [[X:%.*]], i32 1
-; ANY-NEXT: [[T:%.*]] = trunc i64 [[E]] to i32
-; ANY-NEXT: ret i32 [[T]]
+; LE-LABEL: @shrinkExtractElt_i64_to_i32_1(
+; LE-NEXT: [[TMP1:%.*]] = bitcast <3 x i64> [[X:%.*]] to <6 x i32>
+; LE-NEXT: [[T:%.*]] = extractelement <6 x i32> [[TMP1]], i32 2
+; LE-NEXT: ret i32 [[T]]
+;
+; BE-LABEL: @shrinkExtractElt_i64_to_i32_1(
+; BE-NEXT: [[TMP1:%.*]] = bitcast <3 x i64> [[X:%.*]] to <6 x i32>
+; BE-NEXT: [[T:%.*]] = extractelement <6 x i32> [[TMP1]], i32 3
+; BE-NEXT: ret i32 [[T]]
;
%e = extractelement <3 x i64> %x, i32 1
%t = trunc i64 %e to i32
@@ -25,10 +35,15 @@ define i32 @shrinkExtractElt_i64_to_i32_1(<3 x i64> %x) {
}
define i32 @shrinkExtractElt_i64_to_i32_2(<3 x i64> %x) {
-; ANY-LABEL: @shrinkExtractElt_i64_to_i32_2(
-; ANY-NEXT: [[E:%.*]] = extractelement <3 x i64> [[X:%.*]], i32 2
-; ANY-NEXT: [[T:%.*]] = trunc i64 [[E]] to i32
-; ANY-NEXT: ret i32 [[T]]
+; LE-LABEL: @shrinkExtractElt_i64_to_i32_2(
+; LE-NEXT: [[TMP1:%.*]] = bitcast <3 x i64> [[X:%.*]] to <6 x i32>
+; LE-NEXT: [[T:%.*]] = extractelement <6 x i32> [[TMP1]], i32 4
+; LE-NEXT: ret i32 [[T]]
+;
+; BE-LABEL: @shrinkExtractElt_i64_to_i32_2(
+; BE-NEXT: [[TMP1:%.*]] = bitcast <3 x i64> [[X:%.*]] to <6 x i32>
+; BE-NEXT: [[T:%.*]] = extractelement <6 x i32> [[TMP1]], i32 5
+; BE-NEXT: ret i32 [[T]]
;
%e = extractelement <3 x i64> %x, i32 2
%t = trunc i64 %e to i32
@@ -36,10 +51,15 @@ define i32 @shrinkExtractElt_i64_to_i32_2(<3 x i64> %x) {
}
define i16 @shrinkExtractElt_i64_to_i16_0(<3 x i64> %x) {
-; ANY-LABEL: @shrinkExtractElt_i64_to_i16_0(
-; ANY-NEXT: [[E:%.*]] = extractelement <3 x i64> [[X:%.*]], i16 0
-; ANY-NEXT: [[T:%.*]] = trunc i64 [[E]] to i16
-; ANY-NEXT: ret i16 [[T]]
+; LE-LABEL: @shrinkExtractElt_i64_to_i16_0(
+; LE-NEXT: [[TMP1:%.*]] = bitcast <3 x i64> [[X:%.*]] to <12 x i16>
+; LE-NEXT: [[T:%.*]] = extractelement <12 x i16> [[TMP1]], i32 0
+; LE-NEXT: ret i16 [[T]]
+;
+; BE-LABEL: @shrinkExtractElt_i64_to_i16_0(
+; BE-NEXT: [[TMP1:%.*]] = bitcast <3 x i64> [[X:%.*]] to <12 x i16>
+; BE-NEXT: [[T:%.*]] = extractelement <12 x i16> [[TMP1]], i32 3
+; BE-NEXT: ret i16 [[T]]
;
%e = extractelement <3 x i64> %x, i16 0
%t = trunc i64 %e to i16
@@ -47,10 +67,15 @@ define i16 @shrinkExtractElt_i64_to_i16_0(<3 x i64> %x) {
}
define i16 @shrinkExtractElt_i64_to_i16_1(<3 x i64> %x) {
-; ANY-LABEL: @shrinkExtractElt_i64_to_i16_1(
-; ANY-NEXT: [[E:%.*]] = extractelement <3 x i64> [[X:%.*]], i16 1
-; ANY-NEXT: [[T:%.*]] = trunc i64 [[E]] to i16
-; ANY-NEXT: ret i16 [[T]]
+; LE-LABEL: @shrinkExtractElt_i64_to_i16_1(
+; LE-NEXT: [[TMP1:%.*]] = bitcast <3 x i64> [[X:%.*]] to <12 x i16>
+; LE-NEXT: [[T:%.*]] = extractelement <12 x i16> [[TMP1]], i32 4
+; LE-NEXT: ret i16 [[T]]
+;
+; BE-LABEL: @shrinkExtractElt_i64_to_i16_1(
+; BE-NEXT: [[TMP1:%.*]] = bitcast <3 x i64> [[X:%.*]] to <12 x i16>
+; BE-NEXT: [[T:%.*]] = extractelement <12 x i16> [[TMP1]], i32 7
+; BE-NEXT: ret i16 [[T]]
;
%e = extractelement <3 x i64> %x, i16 1
%t = trunc i64 %e to i16
@@ -58,10 +83,15 @@ define i16 @shrinkExtractElt_i64_to_i16_1(<3 x i64> %x) {
}
define i16 @shrinkExtractElt_i64_to_i16_2(<3 x i64> %x) {
-; ANY-LABEL: @shrinkExtractElt_i64_to_i16_2(
-; ANY-NEXT: [[E:%.*]] = extractelement <3 x i64> [[X:%.*]], i16 2
-; ANY-NEXT: [[T:%.*]] = trunc i64 [[E]] to i16
-; ANY-NEXT: ret i16 [[T]]
+; LE-LABEL: @shrinkExtractElt_i64_to_i16_2(
+; LE-NEXT: [[TMP1:%.*]] = bitcast <3 x i64> [[X:%.*]] to <12 x i16>
+; LE-NEXT: [[T:%.*]] = extractelement <12 x i16> [[TMP1]], i32 8
+; LE-NEXT: ret i16 [[T]]
+;
+; BE-LABEL: @shrinkExtractElt_i64_to_i16_2(
+; BE-NEXT: [[TMP1:%.*]] = bitcast <3 x i64> [[X:%.*]] to <12 x i16>
+; BE-NEXT: [[T:%.*]] = extractelement <12 x i16> [[TMP1]], i32 11
+; BE-NEXT: ret i16 [[T]]
;
%e = extractelement <3 x i64> %x, i16 2
%t = trunc i64 %e to i16
@@ -70,10 +100,15 @@ define i16 @shrinkExtractElt_i64_to_i16_2(<3 x i64> %x) {
; Crazy types may be ok.
define i11 @shrinkExtractElt_i33_to_11_2(<3 x i33> %x) {
-; ANY-LABEL: @shrinkExtractElt_i33_to_11_2(
-; ANY-NEXT: [[E:%.*]] = extractelement <3 x i33> [[X:%.*]], i16 2
-; ANY-NEXT: [[T:%.*]] = trunc i33 [[E]] to i11
-; ANY-NEXT: ret i11 [[T]]
+; LE-LABEL: @shrinkExtractElt_i33_to_11_2(
+; LE-NEXT: [[TMP1:%.*]] = bitcast <3 x i33> [[X:%.*]] to <9 x i11>
+; LE-NEXT: [[T:%.*]] = extractelement <9 x i11> [[TMP1]], i32 6
+; LE-NEXT: ret i11 [[T]]
+;
+; BE-LABEL: @shrinkExtractElt_i33_to_11_2(
+; BE-NEXT: [[TMP1:%.*]] = bitcast <3 x i33> [[X:%.*]] to <9 x i11>
+; BE-NEXT: [[T:%.*]] = extractelement <9 x i11> [[TMP1]], i32 8
+; BE-NEXT: ret i11 [[T]]
;
%e = extractelement <3 x i33> %x, i16 2
%t = trunc i33 %e to i11
@@ -122,13 +157,17 @@ define i16 @shrinkExtractElt_i64_to_i16_2_extra_use(<3 x i64> %x) {
; Check to ensure PR45314 remains fixed.
define <4 x i64> @PR45314(<4 x i64> %x) {
-; ANY-LABEL: @PR45314(
-; ANY-NEXT: [[E:%.*]] = extractelement <4 x i64> [[X:%.*]], i32 0
-; ANY-NEXT: [[T:%.*]] = trunc i64 [[E]] to i32
-; ANY-NEXT: [[I:%.*]] = insertelement <8 x i32> undef, i32 [[T]], i32 0
-; ANY-NEXT: [[S:%.*]] = shufflevector <8 x i32> [[I]], <8 x i32> undef, <8 x i32> zeroinitializer
-; ANY-NEXT: [[B:%.*]] = bitcast <8 x i32> [[S]] to <4 x i64>
-; ANY-NEXT: ret <4 x i64> [[B]]
+; LE-LABEL: @PR45314(
+; LE-NEXT: [[TMP1:%.*]] = bitcast <4 x i64> [[X:%.*]] to <8 x i32>
+; LE-NEXT: [[S:%.*]] = shufflevector <8 x i32> [[TMP1]], <8 x i32> undef, <8 x i32> zeroinitializer
+; LE-NEXT: [[B:%.*]] = bitcast <8 x i32> [[S]] to <4 x i64>
+; LE-NEXT: ret <4 x i64> [[B]]
+;
+; BE-LABEL: @PR45314(
+; BE-NEXT: [[TMP1:%.*]] = bitcast <4 x i64> [[X:%.*]] to <8 x i32>
+; BE-NEXT: [[S:%.*]] = shufflevector <8 x i32> [[TMP1]], <8 x i32> undef, <8 x i32> <i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1, i32 1>
+; BE-NEXT: [[B:%.*]] = bitcast <8 x i32> [[S]] to <4 x i64>
+; BE-NEXT: ret <4 x i64> [[B]]
;
%e = extractelement <4 x i64> %x, i32 0
%t = trunc i64 %e to i32
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