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InstCombine: Reduce trunc (shl x, K) width.

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llvm-svn: 272987
This commit is contained in:
Matt Arsenault 2016-06-17 04:43:22 +00:00
parent 457501f033
commit 123f827fb9
5 changed files with 139 additions and 10 deletions
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29
lib/Transforms/InstCombine/InstCombineCasts.cpp
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@ -566,11 +566,30 @@ Instruction *InstCombiner::visitTrunc(TruncInst &CI) {
// Transform "trunc (and X, cst)" -> "and (trunc X), cst" so long as the dest
// type isn't non-native.
if (Src->hasOneUse() && isa<IntegerType>(SrcTy) &&
ShouldChangeType(SrcTy, DestTy) &&
match(Src, m_And(m_Value(A), m_ConstantInt(Cst)))) {
Value *NewTrunc = Builder->CreateTrunc(A, DestTy, A->getName() + ".tr");
return BinaryOperator::CreateAnd(NewTrunc,
ConstantExpr::getTrunc(Cst, DestTy));
ShouldChangeType(SrcTy, DestTy)) {
// Transform "trunc (and X, cst)" -> "and (trunc X), cst" so long as the dest
// type isn't non-native.
if (match(Src, m_And(m_Value(A), m_ConstantInt(Cst)))) {
Value *NewTrunc = Builder->CreateTrunc(A, DestTy, A->getName() + ".tr");
return BinaryOperator::CreateAnd(NewTrunc,
ConstantExpr::getTrunc(Cst, DestTy));
}
// Transform "trunc (shl X, cst)" -> "shl (trunc X), cst" so long as the dest
// type isn't non-native and cst < size / 2
if (match(Src, m_Shl(m_Value(A), m_ConstantInt(Cst)))) {
const unsigned Size = A->getType()->getPrimitiveSizeInBits();
if (Cst->getValue().ult(Size / 2)) {
const unsigned DstSize = DestTy->getPrimitiveSizeInBits();
Value *NewTrunc = Builder->CreateTrunc(A, DestTy, A->getName() + ".tr");
return BinaryOperator::CreateWithCopiedFlags(
Instruction::Shl, NewTrunc,
ConstantInt::get(DestTy, Cst->getValue().trunc(DstSize)),
cast<BinaryOperator>(Src));
}
}
}
if (Instruction *I = foldVecTruncToExtElt(CI, *this, DL))

3
test/Transforms/InstCombine/2011-05-28-swapmulsub.ll
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@ -32,7 +32,8 @@ entry:
; CHECK-NOT: mul i32
%mul = mul i32 %sub, -4
; CHECK: sub i32
; CHECK-NEXT: shl
; CHECK-NEXT: trunc i32
; CHECK-NEXT: shl i16
store i32 %mul, i32* %a, align 4
%tmp2 = load i32, i32* %a, align 4
%conv = trunc i32 %tmp2 to i16

2
test/Transforms/InstCombine/cast.ll
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@ -980,7 +980,7 @@ define double @test72(double *%p, i32 %i) {
define double @test73(double *%p, i128 %i) {
; CHECK-LABEL: @test73(
; CHECK-NEXT: [[O:%.*]] = trunc i128 %i to i64
; CHECK-NEXT: [[PP1:%.*]] = getelementptr double, double* %p, i64 [[O]]
; CHECK-NEXT: [[PP1:%.*]] = getelementptr inbounds double, double* %p, i64 [[O]]
; CHECK-NEXT: [[L:%.*]] = load double, double* [[PP1]], align 8
; CHECK-NEXT: ret double [[L]]
;

6
test/Transforms/InstCombine/icmp.ll
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@ -794,9 +794,9 @@ define i1 @test60_addrspacecast_smaller(i8* %foo, i16 %i, i64 %j) {
define i1 @test60_addrspacecast_larger(i8 addrspace(1)* %foo, i32 %i, i16 %j) {
; CHECK-LABEL: @test60_addrspacecast_larger(
; CHECK-NEXT: [[GEP1_IDX:%.*]] = shl nuw i32 %i, 2
; CHECK-NEXT: [[TMP1:%.*]] = trunc i32 [[GEP1_IDX]] to i16
; CHECK-NEXT: [[TMP2:%.*]] = icmp slt i16 [[TMP1]], %j
; CHECK-NEXT: [[TMP1:%.*]] = trunc i32 %i to i16
; CHECK-NEXT: [[SHL:%.*]] = shl nuw i16 [[TMP1]], 2
; CHECK-NEXT: [[TMP2:%.*]] = icmp slt i16 [[SHL]], %j
; CHECK-NEXT: ret i1 [[TMP2]]
;
%bit = addrspacecast i8 addrspace(1)* %foo to i32 addrspace(2)*

109
test/Transforms/InstCombine/trunc.ll
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@ -160,3 +160,112 @@ define i32 @trunc_bitcast3(<4 x i32> %v) {
; CHECK-NEXT: ret i32 %ext
}
; CHECK-LABEL: @trunc_shl_31_i32_i64(
; CHECK: %val.tr = trunc i64 %val to i32
; CHECK-NEXT: shl i32 %val.tr, 31
define i32 @trunc_shl_31_i32_i64(i64 %val) {
%shl = shl i64 %val, 31
%trunc = trunc i64 %shl to i32
ret i32 %trunc
}
; CHECK-LABEL: @trunc_shl_15_i16_i64(
; CHECK: %val.tr = trunc i64 %val to i16
; CHECK-NEXT: shl i16 %val.tr, 15
define i16 @trunc_shl_15_i16_i64(i64 %val) {
%shl = shl i64 %val, 15
%trunc = trunc i64 %shl to i16
ret i16 %trunc
}
; CHECK-LABEL: @trunc_shl_15_i16_i32(
; CHECK: %val.tr = trunc i32 %val to i16
; CHECK-NEXT: shl i16 %val.tr, 15
define i16 @trunc_shl_15_i16_i32(i32 %val) {
%shl = shl i32 %val, 15
%trunc = trunc i32 %shl to i16
ret i16 %trunc
}
; CHECK-LABEL: @trunc_shl_7_i8_i64(
; CHECK: %val.tr = trunc i64 %val to i8
; CHECK-NEXT: shl i8 %val.tr, 7
define i8 @trunc_shl_7_i8_i64(i64 %val) {
%shl = shl i64 %val, 7
%trunc = trunc i64 %shl to i8
ret i8 %trunc
}
; CHECK-LABEL: @trunc_shl_1_i2_i64(
; CHECK: shl i64 %val, 1
; CHECK-NEXT: trunc i64 %shl to i2
define i2 @trunc_shl_1_i2_i64(i64 %val) {
%shl = shl i64 %val, 1
%trunc = trunc i64 %shl to i2
ret i2 %trunc
}
; CHECK-LABEL: @trunc_shl_1_i32_i64(
; CHECK: %val.tr = trunc i64 %val to i32
; CHECK-NEXT: shl i32 %val.tr, 1
define i32 @trunc_shl_1_i32_i64(i64 %val) {
%shl = shl i64 %val, 1
%trunc = trunc i64 %shl to i32
ret i32 %trunc
}
; CHECK-LABEL: @trunc_shl_16_i32_i64(
; CHECK: %val.tr = trunc i64 %val to i32
; CHECK-NEXT: shl i32 %val.tr, 16
define i32 @trunc_shl_16_i32_i64(i64 %val) {
%shl = shl i64 %val, 16
%trunc = trunc i64 %shl to i32
ret i32 %trunc
}
; CHECK-LABEL: @trunc_shl_33_i32_i64(
; CHECK: ret i32 0
define i32 @trunc_shl_33_i32_i64(i64 %val) {
%shl = shl i64 %val, 33
%trunc = trunc i64 %shl to i32
ret i32 %trunc
}
; CHECK-LABEL: @trunc_shl_32_i32_i64(
; CHECK: ret i32 0
define i32 @trunc_shl_32_i32_i64(i64 %val) {
%shl = shl i64 %val, 32
%trunc = trunc i64 %shl to i32
ret i32 %trunc
}
; TODO: Should be able to handle vectors
; CHECK-LABEL: @trunc_shl_16_v2i32_v2i64(
; CHECK: shl <2 x i64>
define <2 x i32> @trunc_shl_16_v2i32_v2i64(<2 x i64> %val) {
%shl = shl <2 x i64> %val, <i64 16, i64 16>
%trunc = trunc <2 x i64> %shl to <2 x i32>
ret <2 x i32> %trunc
}
; CHECK-LABEL: @trunc_shl_nosplat_v2i32_v2i64(
; CHECK: shl <2 x i64>
define <2 x i32> @trunc_shl_nosplat_v2i32_v2i64(<2 x i64> %val) {
%shl = shl <2 x i64> %val, <i64 15, i64 16>
%trunc = trunc <2 x i64> %shl to <2 x i32>
ret <2 x i32> %trunc
}
; CHECK-LABEL: @trunc_shl_31_i32_i64_multi_use(
; CHECK: shl i64 %val, 31
; CHECK-NOT: shl i32
; CHECK: trunc i64 %shl to i32
; CHECK-NOT: shl i32
define void @trunc_shl_31_i32_i64_multi_use(i64 %val, i32 addrspace(1)* %ptr0, i64 addrspace(1)* %ptr1) {
%shl = shl i64 %val, 31
%trunc = trunc i64 %shl to i32
store volatile i32 %trunc, i32 addrspace(1)* %ptr0
store volatile i64 %shl, i64 addrspace(1)* %ptr1
ret void
}