[llvm] r280873 - [InstCombine] use m_APInt to allow icmp (and (sh X, Y), C2), C1 folds for splat constant vectors
Sanjay Patel via llvm-commits
llvm-commits at lists.llvm.org
Wed Sep 7 15:33:03 PDT 2016
Author: spatel
Date: Wed Sep 7 17:33:03 2016
New Revision: 280873
URL: http://llvm.org/viewvc/llvm-project?rev=280873&view=rev
Log:
[InstCombine] use m_APInt to allow icmp (and (sh X, Y), C2), C1 folds for splat constant vectors
Modified:
llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h
llvm/trunk/test/Transforms/InstCombine/apint-shift.ll
llvm/trunk/test/Transforms/InstCombine/apint-shl-trunc.ll
llvm/trunk/test/Transforms/InstCombine/icmp.ll
llvm/trunk/test/Transforms/InstCombine/pr17827.ll
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp?rev=280873&r1=280872&r2=280873&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineCompares.cpp Wed Sep 7 17:33:03 2016
@@ -1386,29 +1386,21 @@ Instruction *InstCombiner::foldICmpXorCo
/// Fold icmp (and (sh X, Y), C2), C1.
Instruction *InstCombiner::foldICmpAndShift(ICmpInst &Cmp, BinaryOperator *And,
- const APInt *C1) {
- // FIXME: This check restricts all folds under here to scalar types.
- ConstantInt *RHS = dyn_cast<ConstantInt>(Cmp.getOperand(1));
- if (!RHS)
- return nullptr;
-
- // FIXME: This could be passed in as APInt.
- auto *C2 = dyn_cast<ConstantInt>(And->getOperand(1));
- if (!C2)
+ const APInt *C1, const APInt *C2) {
+ BinaryOperator *Shift = dyn_cast<BinaryOperator>(And->getOperand(0));
+ if (!Shift || !Shift->isShift())
return nullptr;
// If this is: (X >> C3) & C2 != C1 (where any shift and any compare could
// exist), turn it into (X & (C2 << C3)) != (C1 << C3). This happens a LOT in
// code produced by the clang front-end, for bitfield access.
- BinaryOperator *Shift = dyn_cast<BinaryOperator>(And->getOperand(0));
- if (!Shift || !Shift->isShift())
- return nullptr;
-
// This seemingly simple opportunity to fold away a shift turns out to be
// rather complicated. See PR17827 for details.
- if (auto *ShAmt = dyn_cast<ConstantInt>(Shift->getOperand(1))) {
+ unsigned ShiftOpcode = Shift->getOpcode();
+ bool IsShl = ShiftOpcode == Instruction::Shl;
+ const APInt *C3;
+ if (match(Shift->getOperand(1), m_APInt(C3))) {
bool CanFold = false;
- unsigned ShiftOpcode = Shift->getOpcode();
if (ShiftOpcode == Instruction::AShr) {
// There may be some constraints that make this possible, but nothing
// simple has been discovered yet.
@@ -1418,35 +1410,23 @@ Instruction *InstCombiner::foldICmpAndSh
// also fold a signed comparison if the mask value and comparison value
// are not negative. These constraints may not be obvious, but we can
// prove that they are correct using an SMT solver.
- if (!Cmp.isSigned() || (!C2->isNegative() && !RHS->isNegative()))
+ if (!Cmp.isSigned() || (!C2->isNegative() && !C1->isNegative()))
CanFold = true;
} else if (ShiftOpcode == Instruction::LShr) {
// For a logical right shift, we can fold if the comparison is not signed.
// We can also fold a signed comparison if the shifted mask value and the
// shifted comparison value are not negative. These constraints may not be
// obvious, but we can prove that they are correct using an SMT solver.
- if (!Cmp.isSigned())
+ if (!Cmp.isSigned() ||
+ (!C2->shl(*C3).isNegative() && !C1->shl(*C3).isNegative()))
CanFold = true;
- else {
- ConstantInt *ShiftedAndCst =
- cast<ConstantInt>(ConstantExpr::getShl(C2, ShAmt));
- ConstantInt *ShiftedRHSCst =
- cast<ConstantInt>(ConstantExpr::getShl(RHS, ShAmt));
-
- if (!ShiftedAndCst->isNegative() && !ShiftedRHSCst->isNegative())
- CanFold = true;
- }
}
if (CanFold) {
- Constant *NewCst;
- if (ShiftOpcode == Instruction::Shl)
- NewCst = ConstantExpr::getLShr(RHS, ShAmt);
- else
- NewCst = ConstantExpr::getShl(RHS, ShAmt);
-
+ APInt NewCst = IsShl ? C1->lshr(*C3) : C1->shl(*C3);
+ APInt SameAsC1 = IsShl ? NewCst.shl(*C3) : NewCst.lshr(*C3);
// Check to see if we are shifting out any of the bits being compared.
- if (ConstantExpr::get(ShiftOpcode, NewCst, ShAmt) != RHS) {
+ if (SameAsC1 != *C1) {
// If we shifted bits out, the fold is not going to work out. As a
// special case, check to see if this means that the result is always
// true or false now.
@@ -1455,13 +1435,9 @@ Instruction *InstCombiner::foldICmpAndSh
if (Cmp.getPredicate() == ICmpInst::ICMP_NE)
return replaceInstUsesWith(Cmp, Builder->getTrue());
} else {
- Cmp.setOperand(1, NewCst);
- Constant *NewAndCst;
- if (ShiftOpcode == Instruction::Shl)
- NewAndCst = ConstantExpr::getLShr(C2, ShAmt);
- else
- NewAndCst = ConstantExpr::getShl(C2, ShAmt);
- And->setOperand(1, NewAndCst);
+ Cmp.setOperand(1, ConstantInt::get(And->getType(), NewCst));
+ APInt NewAndCst = IsShl ? C2->lshr(*C3) : C2->shl(*C3);
+ And->setOperand(1, ConstantInt::get(And->getType(), NewAndCst));
And->setOperand(0, Shift->getOperand(0));
Worklist.Add(Shift); // Shift is dead.
return &Cmp;
@@ -1475,18 +1451,12 @@ Instruction *InstCombiner::foldICmpAndSh
if (Shift->hasOneUse() && *C1 == 0 && Cmp.isEquality() &&
!Shift->isArithmeticShift() && !isa<Constant>(Shift->getOperand(0))) {
// Compute C2 << Y.
- Value *NS;
- if (Shift->getOpcode() == Instruction::LShr) {
- NS = Builder->CreateShl(C2, Shift->getOperand(1));
- } else {
- // Insert a logical shift.
- NS = Builder->CreateLShr(C2, Shift->getOperand(1));
- }
+ Value *NewShift =
+ IsShl ? Builder->CreateLShr(And->getOperand(1), Shift->getOperand(1))
+ : Builder->CreateShl(And->getOperand(1), Shift->getOperand(1));
// Compute X & (C2 << Y).
- Value *NewAnd =
- Builder->CreateAnd(Shift->getOperand(0), NS, And->getName());
-
+ Value *NewAnd = Builder->CreateAnd(Shift->getOperand(0), NewShift);
Cmp.setOperand(0, NewAnd);
return &Cmp;
}
@@ -1529,7 +1499,7 @@ Instruction *InstCombiner::foldICmpAndCo
}
}
- if (Instruction *I = foldICmpAndShift(Cmp, And, C1))
+ if (Instruction *I = foldICmpAndShift(Cmp, And, C1, C2))
return I;
// (icmp pred (and (or (lshr A, B), A), 1), 0) -->
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h?rev=280873&r1=280872&r2=280873&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h Wed Sep 7 17:33:03 2016
@@ -582,7 +582,7 @@ private:
Instruction *foldICmpAndConstConst(ICmpInst &Cmp, BinaryOperator *And,
const APInt *C1);
Instruction *foldICmpAndShift(ICmpInst &Cmp, BinaryOperator *And,
- const APInt *C1);
+ const APInt *C1, const APInt *C2);
Instruction *foldICmpEqualityWithConstant(ICmpInst &ICI);
Instruction *foldICmpIntrinsicWithConstant(ICmpInst &ICI);
Modified: llvm/trunk/test/Transforms/InstCombine/apint-shift.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/apint-shift.ll?rev=280873&r1=280872&r2=280873&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/apint-shift.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/apint-shift.ll Wed Sep 7 17:33:03 2016
@@ -205,11 +205,9 @@ define i1 @test16(i84 %X) {
ret i1 %cmp
}
-; FIXME: Vectors should fold too.
define <2 x i1> @test16vec(<2 x i84> %X) {
; CHECK-LABEL: @test16vec(
-; CHECK-NEXT: [[SHR1:%.*]] = lshr <2 x i84> %X, <i84 4, i84 4>
-; CHECK-NEXT: [[AND:%.*]] = and <2 x i84> [[SHR1]], <i84 1, i84 1>
+; CHECK-NEXT: [[AND:%.*]] = and <2 x i84> %X, <i84 16, i84 16>
; CHECK-NEXT: [[CMP:%.*]] = icmp ne <2 x i84> [[AND]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[CMP]]
;
Modified: llvm/trunk/test/Transforms/InstCombine/apint-shl-trunc.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/apint-shl-trunc.ll?rev=280873&r1=280872&r2=280873&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/apint-shl-trunc.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/apint-shl-trunc.ll Wed Sep 7 17:33:03 2016
@@ -25,12 +25,11 @@ define i1 @test1(i799 %X, i799 %A) {
ret i1 %D
}
-; FIXME: Vectors should fold the same way.
define <2 x i1> @test0vec(<2 x i39> %X, <2 x i39> %A) {
; CHECK-LABEL: @test0vec(
-; CHECK-NEXT: [[B:%.*]] = lshr <2 x i39> %X, %A
-; CHECK-NEXT: [[TMP1:%.*]] = and <2 x i39> [[B]], <i39 1, i39 1>
-; CHECK-NEXT: [[D:%.*]] = icmp ne <2 x i39> [[TMP1]], zeroinitializer
+; CHECK-NEXT: [[TMP1:%.*]] = shl <2 x i39> <i39 1, i39 1>, %A
+; CHECK-NEXT: [[TMP2:%.*]] = and <2 x i39> [[TMP1]], %X
+; CHECK-NEXT: [[D:%.*]] = icmp ne <2 x i39> [[TMP2]], zeroinitializer
; CHECK-NEXT: ret <2 x i1> [[D]]
;
%B = lshr <2 x i39> %X, %A
Modified: llvm/trunk/test/Transforms/InstCombine/icmp.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/icmp.ll?rev=280873&r1=280872&r2=280873&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/icmp.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/icmp.ll Wed Sep 7 17:33:03 2016
@@ -1521,12 +1521,10 @@ define i1 @icmp_add_and_shr_ne_0(i32 %X)
ret i1 %tobool
}
-; FIXME: Vectors should fold the same way.
define <2 x i1> @icmp_add_and_shr_ne_0_vec(<2 x i32> %X) {
; CHECK-LABEL: @icmp_add_and_shr_ne_0_vec(
-; CHECK-NEXT: [[SHR:%.*]] = lshr <2 x i32> %X, <i32 4, i32 4>
-; CHECK-NEXT: [[AND:%.*]] = and <2 x i32> [[SHR]], <i32 15, i32 15>
-; CHECK-NEXT: [[TOBOOL:%.*]] = icmp ne <2 x i32> [[AND]], <i32 14, i32 14>
+; CHECK-NEXT: [[AND:%.*]] = and <2 x i32> %X, <i32 240, i32 240>
+; CHECK-NEXT: [[TOBOOL:%.*]] = icmp ne <2 x i32> [[AND]], <i32 224, i32 224>
; CHECK-NEXT: ret <2 x i1> [[TOBOOL]]
;
%shr = lshr <2 x i32> %X, <i32 4, i32 4>
Modified: llvm/trunk/test/Transforms/InstCombine/pr17827.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/pr17827.ll?rev=280873&r1=280872&r2=280873&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/pr17827.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/pr17827.ll Wed Sep 7 17:33:03 2016
@@ -80,12 +80,11 @@ define i1 @test_shift_and_cmp_changed2(i
ret i1 %cmp
}
-; FIXME: Vectors should fold the same way.
+; FIXME: icmp ult X, 1 -> icmp eq X, 0
define <2 x i1> @test_shift_and_cmp_changed2_vec(<2 x i8> %p) {
; CHECK-LABEL: @test_shift_and_cmp_changed2_vec(
-; CHECK-NEXT: [[SHLP:%.*]] = shl <2 x i8> %p, <i8 5, i8 5>
-; CHECK-NEXT: [[ANDP:%.*]] = and <2 x i8> [[SHLP]], <i8 -64, i8 -64>
-; CHECK-NEXT: [[CMP:%.*]] = icmp ult <2 x i8> [[ANDP]], <i8 32, i8 32>
+; CHECK-NEXT: [[ANDP:%.*]] = and <2 x i8> %p, <i8 6, i8 6>
+; CHECK-NEXT: [[CMP:%.*]] = icmp ult <2 x i8> [[ANDP]], <i8 1, i8 1>
; CHECK-NEXT: ret <2 x i1> [[CMP]]
;
%shlp = shl <2 x i8> %p, <i8 5, i8 5>
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