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InstCombine: Preserve nuw when reassociating nuw ops [3/3] 

Alive says this is OK.

llvm-svn: 364235
This commit is contained in:
Matt Arsenault 2019-06-24 21:37:03 +00:00
parent 5d82ecd5d9
commit 8025842599
2 changed files with 77 additions and 17 deletions
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42
llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
View File

@ -590,32 +590,44 @@ Value *InstCombiner::tryFactorization(BinaryOperator &I,
++NumFactor;
SimplifiedInst->takeName(&I);
// Check if we can add NSW flag to SimplifiedInst. If so, set NSW flag.
// TODO: Check for NUW.
// Check if we can add NSW/NUW flags to SimplifiedInst. If so, set them.
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(SimplifiedInst)) {
if (isa<OverflowingBinaryOperator>(SimplifiedInst)) {
bool HasNSW = false;
if (isa<OverflowingBinaryOperator>(&I))
bool HasNUW = false;
if (isa<OverflowingBinaryOperator>(&I)) {
HasNSW = I.hasNoSignedWrap();
HasNUW = I.hasNoUnsignedWrap();
}
if (auto *LOBO = dyn_cast<OverflowingBinaryOperator>(LHS))
if (auto *LOBO = dyn_cast<OverflowingBinaryOperator>(LHS)) {
HasNSW &= LOBO->hasNoSignedWrap();
HasNUW &= LOBO->hasNoUnsignedWrap();
}
if (auto *ROBO = dyn_cast<OverflowingBinaryOperator>(RHS))
if (auto *ROBO = dyn_cast<OverflowingBinaryOperator>(RHS)) {
HasNSW &= ROBO->hasNoSignedWrap();
HasNUW &= ROBO->hasNoUnsignedWrap();
}
// We can propagate 'nsw' if we know that
// %Y = mul nsw i16 %X, C
// %Z = add nsw i16 %Y, %X
// =>
// %Z = mul nsw i16 %X, C+1
//
// iff C+1 isn't INT_MIN
const APInt *CInt;
if (TopLevelOpcode == Instruction::Add &&
InnerOpcode == Instruction::Mul)
if (match(V, m_APInt(CInt)) && !CInt->isMinSignedValue())
BO->setHasNoSignedWrap(HasNSW);
InnerOpcode == Instruction::Mul) {
// We can propagate 'nsw' if we know that
// %Y = mul nsw i16 %X, C
// %Z = add nsw i16 %Y, %X
// =>
// %Z = mul nsw i16 %X, C+1
//
// iff C+1 isn't INT_MIN
if (match(V, m_APInt(CInt))) {
if (!CInt->isMinSignedValue())
BO->setHasNoSignedWrap(HasNSW);
}
// nuw can be propagated with any constant or nuw value.
BO->setHasNoUnsignedWrap(HasNUW);
}
}
}
}

52
llvm/test/Transforms/InstCombine/reassociate-nuw.ll
View File

@ -92,7 +92,7 @@ define i32 @reassoc_x2_sub_nuw(i32 %x, i32 %y) {
define i32 @tryFactorization_add_nuw_mul_nuw(i32 %x) {
; CHECK-LABEL: @tryFactorization_add_nuw_mul_nuw(
; CHECK-NEXT: [[ADD2:%.*]] = shl i32 [[X:%.*]], 2
; CHECK-NEXT: [[ADD2:%.*]] = shl nuw i32 [[X:%.*]], 2
; CHECK-NEXT: ret i32 [[ADD2]]
;
%mul1 = mul nuw i32 %x, 3
@ -102,7 +102,7 @@ define i32 @tryFactorization_add_nuw_mul_nuw(i32 %x) {
define i32 @tryFactorization_add_nuw_mul_nuw_int_max(i32 %x) {
; CHECK-LABEL: @tryFactorization_add_nuw_mul_nuw_int_max(
; CHECK-NEXT: [[ADD2:%.*]] = shl i32 [[X:%.*]], 31
; CHECK-NEXT: [[ADD2:%.*]] = shl nuw i32 [[X:%.*]], 31
; CHECK-NEXT: ret i32 [[ADD2]]
;
%mul1 = mul nuw i32 %x, 2147483647
@ -129,3 +129,51 @@ define i32 @tryFactorization_add_nuw_mul(i32 %x) {
%add2 = add i32 %mul1, %x
ret i32 %add2
}
define i32 @tryFactorization_add_nuw_mul_nuw_mul_nuw_var(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @tryFactorization_add_nuw_mul_nuw_mul_nuw_var(
; CHECK-NEXT: [[MUL21:%.*]] = add i32 [[Y:%.*]], [[Z:%.*]]
; CHECK-NEXT: [[ADD1:%.*]] = mul nuw i32 [[MUL21]], [[X:%.*]]
; CHECK-NEXT: ret i32 [[ADD1]]
;
%mul1 = mul nuw i32 %x, %y
%mul2 = mul nuw i32 %x, %z
%add1 = add nuw i32 %mul1, %mul2
ret i32 %add1
}
define i32 @tryFactorization_add_nuw_mul_mul_nuw_var(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @tryFactorization_add_nuw_mul_mul_nuw_var(
; CHECK-NEXT: [[MUL21:%.*]] = add i32 [[Y:%.*]], [[Z:%.*]]
; CHECK-NEXT: [[ADD1:%.*]] = mul i32 [[MUL21]], [[X:%.*]]
; CHECK-NEXT: ret i32 [[ADD1]]
;
%mul1 = mul i32 %x, %y
%mul2 = mul nuw i32 %x, %z
%add1 = add nuw i32 %mul1, %mul2
ret i32 %add1
}
define i32 @tryFactorization_add_nuw_mul_nuw_mul_var(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @tryFactorization_add_nuw_mul_nuw_mul_var(
; CHECK-NEXT: [[MUL21:%.*]] = add i32 [[Y:%.*]], [[Z:%.*]]
; CHECK-NEXT: [[ADD1:%.*]] = mul i32 [[MUL21]], [[X:%.*]]
; CHECK-NEXT: ret i32 [[ADD1]]
;
%mul1 = mul nuw i32 %x, %y
%mul2 = mul i32 %x, %z
%add1 = add nuw i32 %mul1, %mul2
ret i32 %add1
}
define i32 @tryFactorization_add_mul_nuw_mul_var(i32 %x, i32 %y, i32 %z) {
; CHECK-LABEL: @tryFactorization_add_mul_nuw_mul_var(
; CHECK-NEXT: [[MUL21:%.*]] = add i32 [[Y:%.*]], [[Z:%.*]]
; CHECK-NEXT: [[ADD1:%.*]] = mul i32 [[MUL21]], [[X:%.*]]
; CHECK-NEXT: ret i32 [[ADD1]]
;
%mul1 = mul nuw i32 %x, %y
%mul2 = mul nuw i32 %x, %z
%add1 = add i32 %mul1, %mul2
ret i32 %add1
}