[llvm] r337642 - [InstrSimplify] fold sdiv if two operands are negated and non-overflow
Chen Zheng via llvm-commits
llvm-commits at lists.llvm.org
Sat Jul 21 05:27:54 PDT 2018
Author: shchenz
Date: Sat Jul 21 05:27:54 2018
New Revision: 337642
URL: http://llvm.org/viewvc/llvm-project?rev=337642&view=rev
Log:
[InstrSimplify] fold sdiv if two operands are negated and non-overflow
Differential Revision: https://reviews.llvm.org/D49382
Modified:
llvm/trunk/include/llvm/Analysis/ValueTracking.h
llvm/trunk/lib/Analysis/InstructionSimplify.cpp
llvm/trunk/lib/Analysis/ValueTracking.cpp
llvm/trunk/test/Transforms/InstSimplify/sdiv.ll
Modified: llvm/trunk/include/llvm/Analysis/ValueTracking.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/ValueTracking.h?rev=337642&r1=337641&r2=337642&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/ValueTracking.h (original)
+++ llvm/trunk/include/llvm/Analysis/ValueTracking.h Sat Jul 21 05:27:54 2018
@@ -102,7 +102,10 @@ class Value;
const DominatorTree *DT = nullptr);
/// Return true if the two given values are negation.
- bool isKnownNegation(const Value *X, const Value *Y);
+ /// Currently can recoginze Value pair:
+ /// 1: <X, Y> if X = sub (0, Y) or Y = sub (0, X)
+ /// 2: <X, Y> if X = sub (A, B) and Y = sub (B, A)
+ bool isKnownNegation(const Value *X, const Value *Y, bool NeedNSW = false);
/// Returns true if the give value is known to be non-negative.
bool isKnownNonNegative(const Value *V, const DataLayout &DL,
Modified: llvm/trunk/lib/Analysis/InstructionSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/InstructionSimplify.cpp?rev=337642&r1=337641&r2=337642&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
+++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Sat Jul 21 05:27:54 2018
@@ -1081,6 +1081,10 @@ static Value *simplifyRem(Instruction::B
/// If not, this returns null.
static Value *SimplifySDivInst(Value *Op0, Value *Op1, const SimplifyQuery &Q,
unsigned MaxRecurse) {
+ // If two operands are negated and no signed overflow, return -1.
+ if (isKnownNegation(Op0, Op1, /*NeedNSW=*/true))
+ return Constant::getAllOnesValue(Op0->getType());
+
return simplifyDiv(Instruction::SDiv, Op0, Op1, Q, MaxRecurse);
}
@@ -1111,7 +1115,7 @@ static Value *SimplifySRemInst(Value *Op
// If the two operands are negated, return 0.
if (isKnownNegation(Op0, Op1))
- return ConstantInt::getNullValue(Op0->getType());
+ return ConstantInt::getNullValue(Op0->getType());
return simplifyRem(Instruction::SRem, Op0, Op1, Q, MaxRecurse);
}
Modified: llvm/trunk/lib/Analysis/ValueTracking.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/ValueTracking.cpp?rev=337642&r1=337641&r2=337642&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/ValueTracking.cpp (original)
+++ llvm/trunk/lib/Analysis/ValueTracking.cpp Sat Jul 21 05:27:54 2018
@@ -4511,21 +4511,25 @@ static SelectPatternResult matchMinMax(C
return {SPF_UNKNOWN, SPNB_NA, false};
}
-bool llvm::isKnownNegation(const Value *X, const Value *Y) {
+bool llvm::isKnownNegation(const Value *X, const Value *Y, bool NeedNSW) {
assert(X && Y && "Invalid operand");
- // X = sub (0, Y)
- if (match(X, m_Neg(m_Specific(Y))))
+ // X = sub (0, Y) || X = sub nsw (0, Y)
+ if ((!NeedNSW && match(X, m_Sub(m_ZeroInt(), m_Specific(Y)))) ||
+ (NeedNSW && match(X, m_NSWSub(m_ZeroInt(), m_Specific(Y)))))
return true;
- // Y = sub (0, X)
- if (match(Y, m_Neg(m_Specific(X))))
+ // Y = sub (0, X) || Y = sub nsw (0, X)
+ if ((!NeedNSW && match(Y, m_Sub(m_ZeroInt(), m_Specific(X)))) ||
+ (NeedNSW && match(Y, m_NSWSub(m_ZeroInt(), m_Specific(X)))))
return true;
- // X = sub (A, B), Y = sub (B, A)
+ // X = sub (A, B), Y = sub (B, A) || X = sub nsw (A, B), Y = sub nsw (B, A)
Value *A, *B;
- return match(X, m_Sub(m_Value(A), m_Value(B))) &&
- match(Y, m_Sub(m_Specific(B), m_Specific(A)));
+ return (!NeedNSW && (match(X, m_Sub(m_Value(A), m_Value(B))) &&
+ match(Y, m_Sub(m_Specific(B), m_Specific(A))))) ||
+ (NeedNSW && (match(X, m_NSWSub(m_Value(A), m_Value(B))) &&
+ match(Y, m_NSWSub(m_Specific(B), m_Specific(A)))));
}
static SelectPatternResult matchSelectPattern(CmpInst::Predicate Pred,
Modified: llvm/trunk/test/Transforms/InstSimplify/sdiv.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstSimplify/sdiv.ll?rev=337642&r1=337641&r2=337642&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstSimplify/sdiv.ll (original)
+++ llvm/trunk/test/Transforms/InstSimplify/sdiv.ll Sat Jul 21 05:27:54 2018
@@ -3,9 +3,7 @@
define i32 @negated_operand(i32 %x) {
; CHECK-LABEL: @negated_operand(
-; CHECK-NEXT: [[NEGX:%.*]] = sub nsw i32 0, [[X:%.*]]
-; CHECK-NEXT: [[DIV:%.*]] = sdiv i32 [[NEGX]], [[X]]
-; CHECK-NEXT: ret i32 [[DIV]]
+; CHECK-NEXT: ret i32 -1
;
%negx = sub nsw i32 0, %x
%div = sdiv i32 %negx, %x
@@ -14,9 +12,7 @@ define i32 @negated_operand(i32 %x) {
define <2 x i32> @negated_operand_commute_vec(<2 x i32> %x) {
; CHECK-LABEL: @negated_operand_commute_vec(
-; CHECK-NEXT: [[NEGX:%.*]] = sub nsw <2 x i32> zeroinitializer, [[X:%.*]]
-; CHECK-NEXT: [[DIV:%.*]] = sdiv <2 x i32> [[NEGX]], [[X]]
-; CHECK-NEXT: ret <2 x i32> [[DIV]]
+; CHECK-NEXT: ret <2 x i32> <i32 -1, i32 -1>
;
%negx = sub nsw <2 x i32> zeroinitializer, %x
%div = sdiv <2 x i32> %negx, %x
@@ -25,10 +21,7 @@ define <2 x i32> @negated_operand_commut
define i32 @knownnegation(i32 %x, i32 %y) {
; CHECK-LABEL: @knownnegation(
-; CHECK-NEXT: [[XY:%.*]] = sub nsw i32 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT: [[YX:%.*]] = sub nsw i32 [[Y]], [[X]]
-; CHECK-NEXT: [[DIV:%.*]] = sdiv i32 [[XY]], [[YX]]
-; CHECK-NEXT: ret i32 [[DIV]]
+; CHECK-NEXT: ret i32 -1
;
%xy = sub nsw i32 %x, %y
%yx = sub nsw i32 %y, %x
@@ -38,10 +31,7 @@ define i32 @knownnegation(i32 %x, i32 %y
define <2 x i32> @knownnegation_commute_vec(<2 x i32> %x, <2 x i32> %y) {
; CHECK-LABEL: @knownnegation_commute_vec(
-; CHECK-NEXT: [[XY:%.*]] = sub nsw <2 x i32> [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT: [[YX:%.*]] = sub nsw <2 x i32> [[Y]], [[X]]
-; CHECK-NEXT: [[DIV:%.*]] = sdiv <2 x i32> [[XY]], [[YX]]
-; CHECK-NEXT: ret <2 x i32> [[DIV]]
+; CHECK-NEXT: ret <2 x i32> <i32 -1, i32 -1>
;
%xy = sub nsw <2 x i32> %x, %y
%yx = sub nsw <2 x i32> %y, %x
@@ -51,10 +41,7 @@ define <2 x i32> @knownnegation_commute_
define i32 @negated_operand_2(i32 %t) {
; CHECK-LABEL: @negated_operand_2(
-; CHECK-NEXT: [[X:%.*]] = sub i32 [[T:%.*]], 5
-; CHECK-NEXT: [[NEGX:%.*]] = sub nsw i32 0, [[X]]
-; CHECK-NEXT: [[DIV:%.*]] = sdiv i32 [[NEGX]], [[X]]
-; CHECK-NEXT: ret i32 [[DIV]]
+; CHECK-NEXT: ret i32 -1
;
%x = sub i32 %t, 5
%negx = sub nsw i32 0, %x
@@ -64,9 +51,7 @@ define i32 @negated_operand_2(i32 %t) {
define i32 @negated_operand_commute(i32 %x) {
; CHECK-LABEL: @negated_operand_commute(
-; CHECK-NEXT: [[NEGX:%.*]] = sub nsw i32 0, [[X]]
-; CHECK-NEXT: [[DIV:%.*]] = sdiv i32 [[X]], [[NEGX]]
-; CHECK-NEXT: ret i32 [[DIV]]
+; CHECK-NEXT: ret i32 -1
;
%negx = sub nsw i32 0, %x
%div = sdiv i32 %x, %negx
@@ -175,9 +160,7 @@ define <2 x i32> @knownnegation_commute_
define <3 x i32> @negated_operand_vec_undef(<3 x i32> %x) {
; CHECK-LABEL: @negated_operand_vec_undef(
-; CHECK-NEXT: [[NEGX:%.*]] = sub nsw <3 x i32> <i32 0, i32 undef, i32 0>, [[X:%.*]]
-; CHECK-NEXT: [[DIV:%.*]] = sdiv <3 x i32> [[NEGX]], [[X]]
-; CHECK-NEXT: ret <3 x i32> [[DIV]]
+; CHECK-NEXT: ret <3 x i32> <i32 -1, i32 -1, i32 -1>
;
%negx = sub nsw <3 x i32> <i32 0, i32 undef, i32 0>, %x
%div = sdiv <3 x i32> %negx, %x
More information about the llvm-commits
mailing list