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Revert "[InstCombine] Recognize ((x * y) s/ x) !=/== y as an signed multiplication overflow check (PR48769)"

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This reverts commit 13ec913bdf500e2354cc55bf29e2f5d99e0c709e.

This commit introduces new uses of the overflow checking intrinsics that
depend on implementations in compiler-rt, which Windows users generally
do not link against. I filed an issue (somewhere) to make clang
auto-link the builtins library to resolve this situation, but until that
happens, it isn't reasonable for the optimizer to introduce new link
time dependencies.
This commit is contained in:
Reid Kleckner 2021-04-20 15:53:34 -07:00
parent 5209f18c1c
commit 9055783420
4 changed files with 66 additions and 71 deletions
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39
lib/Transforms/InstCombine/InstCombineCompares.cpp
View File

@ -3672,22 +3672,19 @@ foldShiftIntoShiftInAnotherHandOfAndInICmp(ICmpInst &I, const SimplifyQuery SQ,
/// Fold
/// (-1 u/ x) u< y
/// ((x * y) ?/ x) != y
/// ((x * y) u/ x) != y
/// to
/// @llvm.?mul.with.overflow(x, y) plus extraction of overflow bit
/// @llvm.umul.with.overflow(x, y) plus extraction of overflow bit
/// Note that the comparison is commutative, while inverted (u>=, ==) predicate
/// will mean that we are looking for the opposite answer.
Value *InstCombinerImpl::foldMultiplicationOverflowCheck(ICmpInst &I) {
Value *InstCombinerImpl::foldUnsignedMultiplicationOverflowCheck(ICmpInst &I) {
ICmpInst::Predicate Pred;
Value *X, *Y;
Instruction *Mul;
Instruction *Div;
bool NeedNegation;
// Look for: (-1 u/ x) u</u>= y
if (!I.isEquality() &&
match(&I, m_c_ICmp(Pred,
m_CombineAnd(m_OneUse(m_UDiv(m_AllOnes(), m_Value(X))),
m_Instruction(Div)),
match(&I, m_c_ICmp(Pred, m_OneUse(m_UDiv(m_AllOnes(), m_Value(X))),
m_Value(Y)))) {
Mul = nullptr;
@ -3702,16 +3699,13 @@ Value *InstCombinerImpl::foldMultiplicationOverflowCheck(ICmpInst &I) {
default:
return nullptr; // Wrong predicate.
}
} else // Look for: ((x * y) / x) !=/== y
} else // Look for: ((x * y) u/ x) !=/== y
if (I.isEquality() &&
match(&I,
m_c_ICmp(Pred, m_Value(Y),
m_CombineAnd(
m_OneUse(m_IDiv(m_CombineAnd(m_c_Mul(m_Deferred(Y),
match(&I, m_c_ICmp(Pred, m_Value(Y),
m_OneUse(m_UDiv(m_CombineAnd(m_c_Mul(m_Deferred(Y),
m_Value(X)),
m_Instruction(Mul)),
m_Deferred(X))),
m_Instruction(Div))))) {
m_Deferred(X)))))) {
NeedNegation = Pred == ICmpInst::Predicate::ICMP_EQ;
} else
return nullptr;
@ -3723,22 +3717,19 @@ Value *InstCombinerImpl::foldMultiplicationOverflowCheck(ICmpInst &I) {
if (MulHadOtherUses)
Builder.SetInsertPoint(Mul);
Function *F = Intrinsic::getDeclaration(I.getModule(),
Div->getOpcode() == Instruction::UDiv
? Intrinsic::umul_with_overflow
: Intrinsic::smul_with_overflow,
X->getType());
CallInst *Call = Builder.CreateCall(F, {X, Y}, "mul");
Function *F = Intrinsic::getDeclaration(
I.getModule(), Intrinsic::umul_with_overflow, X->getType());
CallInst *Call = Builder.CreateCall(F, {X, Y}, "umul");
// If the multiplication was used elsewhere, to ensure that we don't leave
// "duplicate" instructions, replace uses of that original multiplication
// with the multiplication result from the with.overflow intrinsic.
if (MulHadOtherUses)
replaceInstUsesWith(*Mul, Builder.CreateExtractValue(Call, 0, "mul.val"));
replaceInstUsesWith(*Mul, Builder.CreateExtractValue(Call, 0, "umul.val"));
Value *Res = Builder.CreateExtractValue(Call, 1, "mul.ov");
Value *Res = Builder.CreateExtractValue(Call, 1, "umul.ov");
if (NeedNegation) // This technically increases instruction count.
Res = Builder.CreateNot(Res, "mul.not.ov");
Res = Builder.CreateNot(Res, "umul.not.ov");
// If we replaced the mul, erase it. Do this after all uses of Builder,
// as the mul is used as insertion point.
@ -4135,7 +4126,7 @@ Instruction *InstCombinerImpl::foldICmpBinOp(ICmpInst &I,
}
}
if (Value *V = foldMultiplicationOverflowCheck(I))
if (Value *V = foldUnsignedMultiplicationOverflowCheck(I))
return replaceInstUsesWith(I, V);
if (Value *V = foldICmpWithLowBitMaskedVal(I, Builder))

2
lib/Transforms/InstCombine/InstCombineInternal.h
View File

@ -656,7 +656,7 @@ public:
Instruction *foldSignBitTest(ICmpInst &I);
Instruction *foldICmpWithZero(ICmpInst &Cmp);
Value *foldMultiplicationOverflowCheck(ICmpInst &Cmp);
Value *foldUnsignedMultiplicationOverflowCheck(ICmpInst &Cmp);
Instruction *foldICmpSelectConstant(ICmpInst &Cmp, SelectInst *Select,
ConstantInt *C);

51
test/Transforms/InstCombine/signed-mul-lack-of-overflow-check-via-mul-sdiv.ll
View File

@ -8,10 +8,10 @@
define i1 @t0_basic(i8 %x, i8 %y) {
; CHECK-LABEL: @t0_basic(
; CHECK-NEXT: [[MUL:%.*]] = call { i8, i1 } @llvm.smul.with.overflow.i8(i8 [[X:%.*]], i8 [[Y:%.*]])
; CHECK-NEXT: [[MUL_OV:%.*]] = extractvalue { i8, i1 } [[MUL]], 1
; CHECK-NEXT: [[MUL_NOT_OV:%.*]] = xor i1 [[MUL_OV]], true
; CHECK-NEXT: ret i1 [[MUL_NOT_OV]]
; CHECK-NEXT: [[T0:%.*]] = mul i8 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[T1:%.*]] = sdiv i8 [[T0]], [[X]]
; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[T1]], [[Y]]
; CHECK-NEXT: ret i1 [[R]]
;
%t0 = mul i8 %x, %y
%t1 = sdiv i8 %t0, %x
@ -21,10 +21,10 @@ define i1 @t0_basic(i8 %x, i8 %y) {
define <2 x i1> @t1_vec(<2 x i8> %x, <2 x i8> %y) {
; CHECK-LABEL: @t1_vec(
; CHECK-NEXT: [[MUL:%.*]] = call { <2 x i8>, <2 x i1> } @llvm.smul.with.overflow.v2i8(<2 x i8> [[X:%.*]], <2 x i8> [[Y:%.*]])
; CHECK-NEXT: [[MUL_OV:%.*]] = extractvalue { <2 x i8>, <2 x i1> } [[MUL]], 1
; CHECK-NEXT: [[MUL_NOT_OV:%.*]] = xor <2 x i1> [[MUL_OV]], <i1 true, i1 true>
; CHECK-NEXT: ret <2 x i1> [[MUL_NOT_OV]]
; CHECK-NEXT: [[T0:%.*]] = mul <2 x i8> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[T1:%.*]] = sdiv <2 x i8> [[T0]], [[X]]
; CHECK-NEXT: [[R:%.*]] = icmp eq <2 x i8> [[T1]], [[Y]]
; CHECK-NEXT: ret <2 x i1> [[R]]
;
%t0 = mul <2 x i8> %x, %y
%t1 = sdiv <2 x i8> %t0, %x
@ -37,10 +37,10 @@ declare i8 @gen8()
define i1 @t2_commutative(i8 %x) {
; CHECK-LABEL: @t2_commutative(
; CHECK-NEXT: [[Y:%.*]] = call i8 @gen8()
; CHECK-NEXT: [[MUL:%.*]] = call { i8, i1 } @llvm.smul.with.overflow.i8(i8 [[X:%.*]], i8 [[Y]])
; CHECK-NEXT: [[MUL_OV:%.*]] = extractvalue { i8, i1 } [[MUL]], 1
; CHECK-NEXT: [[MUL_NOT_OV:%.*]] = xor i1 [[MUL_OV]], true
; CHECK-NEXT: ret i1 [[MUL_NOT_OV]]
; CHECK-NEXT: [[T0:%.*]] = mul i8 [[Y]], [[X:%.*]]
; CHECK-NEXT: [[T1:%.*]] = sdiv i8 [[T0]], [[X]]
; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[T1]], [[Y]]
; CHECK-NEXT: ret i1 [[R]]
;
%y = call i8 @gen8()
%t0 = mul i8 %y, %x ; swapped
@ -52,10 +52,10 @@ define i1 @t2_commutative(i8 %x) {
define i1 @t3_commutative(i8 %x) {
; CHECK-LABEL: @t3_commutative(
; CHECK-NEXT: [[Y:%.*]] = call i8 @gen8()
; CHECK-NEXT: [[MUL:%.*]] = call { i8, i1 } @llvm.smul.with.overflow.i8(i8 [[X:%.*]], i8 [[Y]])
; CHECK-NEXT: [[MUL_OV:%.*]] = extractvalue { i8, i1 } [[MUL]], 1
; CHECK-NEXT: [[MUL_NOT_OV:%.*]] = xor i1 [[MUL_OV]], true
; CHECK-NEXT: ret i1 [[MUL_NOT_OV]]
; CHECK-NEXT: [[T0:%.*]] = mul i8 [[Y]], [[X:%.*]]
; CHECK-NEXT: [[T1:%.*]] = sdiv i8 [[T0]], [[X]]
; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[T1]], [[Y]]
; CHECK-NEXT: ret i1 [[R]]
;
%y = call i8 @gen8()
%t0 = mul i8 %y, %x ; swapped
@ -67,10 +67,10 @@ define i1 @t3_commutative(i8 %x) {
define i1 @t4_commutative(i8 %x) {
; CHECK-LABEL: @t4_commutative(
; CHECK-NEXT: [[Y:%.*]] = call i8 @gen8()
; CHECK-NEXT: [[MUL:%.*]] = call { i8, i1 } @llvm.smul.with.overflow.i8(i8 [[X:%.*]], i8 [[Y]])
; CHECK-NEXT: [[MUL_OV:%.*]] = extractvalue { i8, i1 } [[MUL]], 1
; CHECK-NEXT: [[MUL_NOT_OV:%.*]] = xor i1 [[MUL_OV]], true
; CHECK-NEXT: ret i1 [[MUL_NOT_OV]]
; CHECK-NEXT: [[T0:%.*]] = mul i8 [[Y]], [[X:%.*]]
; CHECK-NEXT: [[T1:%.*]] = sdiv i8 [[T0]], [[X]]
; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[Y]], [[T1]]
; CHECK-NEXT: ret i1 [[R]]
;
%y = call i8 @gen8()
%t0 = mul i8 %y, %x ; swapped
@ -85,12 +85,11 @@ declare void @use8(i8)
define i1 @t5_extrause0(i8 %x, i8 %y) {
; CHECK-LABEL: @t5_extrause0(
; CHECK-NEXT: [[MUL:%.*]] = call { i8, i1 } @llvm.smul.with.overflow.i8(i8 [[X:%.*]], i8 [[Y:%.*]])
; CHECK-NEXT: [[MUL_VAL:%.*]] = extractvalue { i8, i1 } [[MUL]], 0
; CHECK-NEXT: [[MUL_OV:%.*]] = extractvalue { i8, i1 } [[MUL]], 1
; CHECK-NEXT: [[MUL_NOT_OV:%.*]] = xor i1 [[MUL_OV]], true
; CHECK-NEXT: call void @use8(i8 [[MUL_VAL]])
; CHECK-NEXT: ret i1 [[MUL_NOT_OV]]
; CHECK-NEXT: [[T0:%.*]] = mul i8 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: call void @use8(i8 [[T0]])
; CHECK-NEXT: [[T1:%.*]] = sdiv i8 [[T0]], [[X]]
; CHECK-NEXT: [[R:%.*]] = icmp eq i8 [[T1]], [[Y]]
; CHECK-NEXT: ret i1 [[R]]
;
%t0 = mul i8 %x, %y
call void @use8(i8 %t0)

45
test/Transforms/InstCombine/signed-mul-overflow-check-via-mul-sdiv.ll
View File

@ -8,9 +8,10 @@
define i1 @t0_basic(i8 %x, i8 %y) {
; CHECK-LABEL: @t0_basic(
; CHECK-NEXT: [[MUL:%.*]] = call { i8, i1 } @llvm.smul.with.overflow.i8(i8 [[X:%.*]], i8 [[Y:%.*]])
; CHECK-NEXT: [[MUL_OV:%.*]] = extractvalue { i8, i1 } [[MUL]], 1
; CHECK-NEXT: ret i1 [[MUL_OV]]
; CHECK-NEXT: [[T0:%.*]] = mul i8 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[T1:%.*]] = sdiv i8 [[T0]], [[X]]
; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[T1]], [[Y]]
; CHECK-NEXT: ret i1 [[R]]
;
%t0 = mul i8 %x, %y
%t1 = sdiv i8 %t0, %x
@ -20,9 +21,10 @@ define i1 @t0_basic(i8 %x, i8 %y) {
define <2 x i1> @t1_vec(<2 x i8> %x, <2 x i8> %y) {
; CHECK-LABEL: @t1_vec(
; CHECK-NEXT: [[MUL:%.*]] = call { <2 x i8>, <2 x i1> } @llvm.smul.with.overflow.v2i8(<2 x i8> [[X:%.*]], <2 x i8> [[Y:%.*]])
; CHECK-NEXT: [[MUL_OV:%.*]] = extractvalue { <2 x i8>, <2 x i1> } [[MUL]], 1
; CHECK-NEXT: ret <2 x i1> [[MUL_OV]]
; CHECK-NEXT: [[T0:%.*]] = mul <2 x i8> [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: [[T1:%.*]] = sdiv <2 x i8> [[T0]], [[X]]
; CHECK-NEXT: [[R:%.*]] = icmp ne <2 x i8> [[T1]], [[Y]]
; CHECK-NEXT: ret <2 x i1> [[R]]
;
%t0 = mul <2 x i8> %x, %y
%t1 = sdiv <2 x i8> %t0, %x
@ -35,9 +37,10 @@ declare i8 @gen8()
define i1 @t2_commutative(i8 %x) {
; CHECK-LABEL: @t2_commutative(
; CHECK-NEXT: [[Y:%.*]] = call i8 @gen8()
; CHECK-NEXT: [[MUL:%.*]] = call { i8, i1 } @llvm.smul.with.overflow.i8(i8 [[X:%.*]], i8 [[Y]])
; CHECK-NEXT: [[MUL_OV:%.*]] = extractvalue { i8, i1 } [[MUL]], 1
; CHECK-NEXT: ret i1 [[MUL_OV]]
; CHECK-NEXT: [[T0:%.*]] = mul i8 [[Y]], [[X:%.*]]
; CHECK-NEXT: [[T1:%.*]] = sdiv i8 [[T0]], [[X]]
; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[T1]], [[Y]]
; CHECK-NEXT: ret i1 [[R]]
;
%y = call i8 @gen8()
%t0 = mul i8 %y, %x ; swapped
@ -49,9 +52,10 @@ define i1 @t2_commutative(i8 %x) {
define i1 @t3_commutative(i8 %x) {
; CHECK-LABEL: @t3_commutative(
; CHECK-NEXT: [[Y:%.*]] = call i8 @gen8()
; CHECK-NEXT: [[MUL:%.*]] = call { i8, i1 } @llvm.smul.with.overflow.i8(i8 [[X:%.*]], i8 [[Y]])
; CHECK-NEXT: [[MUL_OV:%.*]] = extractvalue { i8, i1 } [[MUL]], 1
; CHECK-NEXT: ret i1 [[MUL_OV]]
; CHECK-NEXT: [[T0:%.*]] = mul i8 [[Y]], [[X:%.*]]
; CHECK-NEXT: [[T1:%.*]] = sdiv i8 [[T0]], [[X]]
; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[T1]], [[Y]]
; CHECK-NEXT: ret i1 [[R]]
;
%y = call i8 @gen8()
%t0 = mul i8 %y, %x ; swapped
@ -63,9 +67,10 @@ define i1 @t3_commutative(i8 %x) {
define i1 @t4_commutative(i8 %x) {
; CHECK-LABEL: @t4_commutative(
; CHECK-NEXT: [[Y:%.*]] = call i8 @gen8()
; CHECK-NEXT: [[MUL:%.*]] = call { i8, i1 } @llvm.smul.with.overflow.i8(i8 [[X:%.*]], i8 [[Y]])
; CHECK-NEXT: [[MUL_OV:%.*]] = extractvalue { i8, i1 } [[MUL]], 1
; CHECK-NEXT: ret i1 [[MUL_OV]]
; CHECK-NEXT: [[T0:%.*]] = mul i8 [[Y]], [[X:%.*]]
; CHECK-NEXT: [[T1:%.*]] = sdiv i8 [[T0]], [[X]]
; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[Y]], [[T1]]
; CHECK-NEXT: ret i1 [[R]]
;
%y = call i8 @gen8()
%t0 = mul i8 %y, %x ; swapped
@ -80,11 +85,11 @@ declare void @use8(i8)
define i1 @t5_extrause0(i8 %x, i8 %y) {
; CHECK-LABEL: @t5_extrause0(
; CHECK-NEXT: [[MUL:%.*]] = call { i8, i1 } @llvm.smul.with.overflow.i8(i8 [[X:%.*]], i8 [[Y:%.*]])
; CHECK-NEXT: [[MUL_VAL:%.*]] = extractvalue { i8, i1 } [[MUL]], 0
; CHECK-NEXT: [[MUL_OV:%.*]] = extractvalue { i8, i1 } [[MUL]], 1
; CHECK-NEXT: call void @use8(i8 [[MUL_VAL]])
; CHECK-NEXT: ret i1 [[MUL_OV]]
; CHECK-NEXT: [[T0:%.*]] = mul i8 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: call void @use8(i8 [[T0]])
; CHECK-NEXT: [[T1:%.*]] = sdiv i8 [[T0]], [[X]]
; CHECK-NEXT: [[R:%.*]] = icmp ne i8 [[T1]], [[Y]]
; CHECK-NEXT: ret i1 [[R]]
;
%t0 = mul i8 %x, %y
call void @use8(i8 %t0)