[llvm] 0931145 - [InstCombine] Extend `0 - (X sdiv C) -> (X sdiv -C)` fold to non-splat vectors
Roman Lebedev via llvm-commits
llvm-commits at lists.llvm.org
Thu Dec 5 04:48:42 PST 2019
Author: Roman Lebedev
Date: 2019-12-05T15:48:29+03:00
New Revision: 09311459e3750f9dbd164fe7ea40fd9548571128
URL: https://github.com/llvm/llvm-project/commit/09311459e3750f9dbd164fe7ea40fd9548571128
DIFF: https://github.com/llvm/llvm-project/commit/09311459e3750f9dbd164fe7ea40fd9548571128.diff
LOG: [InstCombine] Extend `0 - (X sdiv C) -> (X sdiv -C)` fold to non-splat vectors
Split off from https://reviews.llvm.org/D68408
Added:
Modified:
llvm/include/llvm/IR/Constant.h
llvm/lib/IR/Constants.cpp
llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
llvm/test/Transforms/InstCombine/div.ll
Removed:
################################################################################
diff --git a/llvm/include/llvm/IR/Constant.h b/llvm/include/llvm/IR/Constant.h
index b91100a0e891..3f3fa4c272c5 100644
--- a/llvm/include/llvm/IR/Constant.h
+++ b/llvm/include/llvm/IR/Constant.h
@@ -53,6 +53,10 @@ class Constant : public User {
/// Returns true if the value is one.
bool isOneValue() const;
+ /// Return true if the value is not the one value, or,
+ /// for vectors, does not contain one value elements.
+ bool isNotOneValue() const;
+
/// Return true if this is the value that would be returned by
/// getAllOnesValue.
bool isAllOnesValue() const;
@@ -64,7 +68,8 @@ class Constant : public User {
/// Return true if the value is negative zero or null value.
bool isZeroValue() const;
- /// Return true if the value is not the smallest signed value.
+ /// Return true if the value is not the smallest signed value, or,
+ /// for vectors, does not contain smallest signed value elements.
bool isNotMinSignedValue() const;
/// Return true if the value is the smallest signed value.
diff --git a/llvm/lib/IR/Constants.cpp b/llvm/lib/IR/Constants.cpp
index b5df4ea8af6c..7ea5cb8b167b 100644
--- a/llvm/lib/IR/Constants.cpp
+++ b/llvm/lib/IR/Constants.cpp
@@ -150,6 +150,30 @@ bool Constant::isOneValue() const {
return false;
}
+bool Constant::isNotOneValue() const {
+ // Check for 1 integers
+ if (const ConstantInt *CI = dyn_cast<ConstantInt>(this))
+ return !CI->isOneValue();
+
+ // Check for FP which are bitcasted from 1 integers
+ if (const ConstantFP *CFP = dyn_cast<ConstantFP>(this))
+ return !CFP->getValueAPF().bitcastToAPInt().isOneValue();
+
+ // Check that vectors don't contain 1
+ if (this->getType()->isVectorTy()) {
+ unsigned NumElts = this->getType()->getVectorNumElements();
+ for (unsigned i = 0; i != NumElts; ++i) {
+ Constant *Elt = this->getAggregateElement(i);
+ if (!Elt || !Elt->isNotOneValue())
+ return false;
+ }
+ return true;
+ }
+
+ // It *may* contain 1, we can't tell.
+ return false;
+}
+
bool Constant::isMinSignedValue() const {
// Check for INT_MIN integers
if (const ConstantInt *CI = dyn_cast<ConstantInt>(this))
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
index 8bc34825f8a7..5b71f9d9c2e3 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -1896,14 +1896,16 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
Builder.CreateNot(Y, Y->getName() + ".not"));
// 0 - (X sdiv C) -> (X sdiv -C) provided the negation doesn't overflow.
- // TODO: This could be extended to match arbitrary vector constants.
- const APInt *DivC;
- if (match(Op0, m_Zero()) && match(Op1, m_SDiv(m_Value(X), m_APInt(DivC))) &&
- !DivC->isMinSignedValue() && *DivC != 1) {
- Constant *NegDivC = ConstantInt::get(I.getType(), -(*DivC));
- Instruction *BO = BinaryOperator::CreateSDiv(X, NegDivC);
- BO->setIsExact(cast<BinaryOperator>(Op1)->isExact());
- return BO;
+ if (match(Op0, m_Zero())) {
+ Constant *Op11C;
+ if (match(Op1, m_SDiv(m_Value(X), m_Constant(Op11C))) &&
+ !Op11C->containsUndefElement() && Op11C->isNotMinSignedValue() &&
+ Op11C->isNotOneValue()) {
+ Instruction *BO =
+ BinaryOperator::CreateSDiv(X, ConstantExpr::getNeg(Op11C));
+ BO->setIsExact(cast<BinaryOperator>(Op1)->isExact());
+ return BO;
+ }
}
// 0 - (X << Y) -> (-X << Y) when X is freely negatable.
diff --git a/llvm/test/Transforms/InstCombine/div.ll b/llvm/test/Transforms/InstCombine/div.ll
index 4c4308151e7f..a4c6139e2106 100644
--- a/llvm/test/Transforms/InstCombine/div.ll
+++ b/llvm/test/Transforms/InstCombine/div.ll
@@ -522,8 +522,7 @@ define <2 x i8> @sdiv_negated_dividend_constant_divisor_vec_undef(<2 x i8> %x) {
define <2 x i64> @sdiv_negated_dividend_constant_divisor_vec(<2 x i64> %x) {
; CHECK-LABEL: @sdiv_negated_dividend_constant_divisor_vec(
-; CHECK-NEXT: [[DIV1:%.*]] = sdiv <2 x i64> [[X:%.*]], <i64 3, i64 4>
-; CHECK-NEXT: [[DIV:%.*]] = sub nsw <2 x i64> zeroinitializer, [[DIV1]]
+; CHECK-NEXT: [[DIV:%.*]] = sdiv <2 x i64> [[X:%.*]], <i64 -3, i64 -4>
; CHECK-NEXT: ret <2 x i64> [[DIV]]
;
%neg = sub nsw <2 x i64> zeroinitializer, %x
@@ -533,8 +532,7 @@ define <2 x i64> @sdiv_negated_dividend_constant_divisor_vec(<2 x i64> %x) {
define <2 x i64> @sdiv_exact_negated_dividend_constant_divisor_vec(<2 x i64> %x) {
; CHECK-LABEL: @sdiv_exact_negated_dividend_constant_divisor_vec(
-; CHECK-NEXT: [[DIV1:%.*]] = sdiv exact <2 x i64> [[X:%.*]], <i64 3, i64 4>
-; CHECK-NEXT: [[DIV:%.*]] = sub nsw <2 x i64> zeroinitializer, [[DIV1]]
+; CHECK-NEXT: [[DIV:%.*]] = sdiv exact <2 x i64> [[X:%.*]], <i64 -3, i64 -4>
; CHECK-NEXT: ret <2 x i64> [[DIV]]
;
%neg = sub nsw <2 x i64> zeroinitializer, %x
@@ -860,8 +858,7 @@ define i32 @test_exact_nsw_exact(i32 %x) {
define <2 x i64> @test_exact_vec(<2 x i64> %x) {
; CHECK-LABEL: @test_exact_vec(
-; CHECK-NEXT: [[DIV:%.*]] = sdiv exact <2 x i64> [[X:%.*]], <i64 3, i64 4>
-; CHECK-NEXT: [[NEG:%.*]] = sub nsw <2 x i64> zeroinitializer, [[DIV]]
+; CHECK-NEXT: [[NEG:%.*]] = sdiv exact <2 x i64> [[X:%.*]], <i64 -3, i64 -4>
; CHECK-NEXT: ret <2 x i64> [[NEG]]
;
%div = sdiv exact <2 x i64> %x, <i64 3, i64 4>
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