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[CVP] Canonicalize signed minmax into unsigned #82478

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Feb 22, 2024
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[CVP] Canonicalize signed minmax into unsigned #82478

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87421b6
[CVP] Add pre-commit tests. NFC.
dtcxzyw Feb 22, 2024
2288a86
[CVP] Canonicalize signed minmax into unsigned
dtcxzyw Feb 22, 2024
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25 changes: 17 additions & 8 deletions llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -47,11 +47,6 @@ using namespace llvm;

#define DEBUG_TYPE "correlated-value-propagation"

static cl::opt<bool> CanonicalizeICmpPredicatesToUnsigned(
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Did something change for the example mentioned in https://reviews.llvm.org/D112895#3149487 to warrant removal of this option?

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The example is optimized by ConstraintElimination now.

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Nice! I expected to find it in the added tests though.

"canonicalize-icmp-predicates-to-unsigned", cl::init(true), cl::Hidden,
cl::desc("Enables canonicalization of signed relational predicates to "
"unsigned (e.g. sgt => ugt)"));

STATISTIC(NumPhis, "Number of phis propagated");
STATISTIC(NumPhiCommon, "Number of phis deleted via common incoming value");
STATISTIC(NumSelects, "Number of selects propagated");
Expand Down Expand Up @@ -90,6 +85,8 @@ STATISTIC(NumSaturating,
"Number of saturating arithmetics converted to normal arithmetics");
STATISTIC(NumNonNull, "Number of function pointer arguments marked non-null");
STATISTIC(NumMinMax, "Number of llvm.[us]{min,max} intrinsics removed");
STATISTIC(NumSMinMax,
"Number of llvm.s{min,max} intrinsics simplified to unsigned");
STATISTIC(NumUDivURemsNarrowedExpanded,
"Number of bound udiv's/urem's expanded");
STATISTIC(NumZExt, "Number of non-negative deductions");
Expand Down Expand Up @@ -289,9 +286,6 @@ static bool processPHI(PHINode *P, LazyValueInfo *LVI, DominatorTree *DT,
}

static bool processICmp(ICmpInst *Cmp, LazyValueInfo *LVI) {
if (!CanonicalizeICmpPredicatesToUnsigned)
return false;

// Only for signed relational comparisons of scalar integers.
if (Cmp->getType()->isVectorTy() ||
!Cmp->getOperand(0)->getType()->isIntegerTy())
Expand Down Expand Up @@ -528,6 +522,7 @@ static bool processAbsIntrinsic(IntrinsicInst *II, LazyValueInfo *LVI) {
}

// See if this min/max intrinsic always picks it's one specific operand.
// If not, check whether we can canonicalize signed minmax into unsigned version
static bool processMinMaxIntrinsic(MinMaxIntrinsic *MM, LazyValueInfo *LVI) {
CmpInst::Predicate Pred = CmpInst::getNonStrictPredicate(MM->getPredicate());
ConstantRange LHS_CR = LVI->getConstantRangeAtUse(MM->getOperandUse(0),
Expand All @@ -546,6 +541,20 @@ static bool processMinMaxIntrinsic(MinMaxIntrinsic *MM, LazyValueInfo *LVI) {
MM->eraseFromParent();
return true;
}

if (MM->isSigned() &&
ConstantRange::areInsensitiveToSignednessOfICmpPredicate(LHS_CR,
RHS_CR)) {
++NumSMinMax;
IRBuilder<> B(MM);
MM->replaceAllUsesWith(B.CreateBinaryIntrinsic(
MM->getIntrinsicID() == Intrinsic::smin ? Intrinsic::umin
: Intrinsic::umax,
MM->getLHS(), MM->getRHS()));
MM->eraseFromParent();
return true;
}

return false;
}

Expand Down
73 changes: 69 additions & 4 deletions llvm/test/Transforms/CorrelatedValuePropagation/min-max.ll
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Original file line number Diff line number Diff line change
Expand Up @@ -176,8 +176,8 @@ define i8 @test15(i8 %x) {
; CHECK-LABEL: @test15(
; CHECK-NEXT: [[LIM:%.*]] = icmp sge i8 [[X:%.*]], 41
; CHECK-NEXT: call void @llvm.assume(i1 [[LIM]])
; CHECK-NEXT: [[R:%.*]] = call i8 @llvm.smin.i8(i8 [[X]], i8 42)
; CHECK-NEXT: ret i8 [[R]]
; CHECK-NEXT: [[TMP1:%.*]] = call i8 @llvm.umin.i8(i8 [[X]], i8 42)
; CHECK-NEXT: ret i8 [[TMP1]]
;
%lim = icmp sge i8 %x, 41
call void @llvm.assume(i1 %lim)
Expand All @@ -189,8 +189,8 @@ define i8 @test16(i8 %x) {
; CHECK-LABEL: @test16(
; CHECK-NEXT: [[LIM:%.*]] = icmp sge i8 [[X:%.*]], 41
; CHECK-NEXT: call void @llvm.assume(i1 [[LIM]])
; CHECK-NEXT: [[R:%.*]] = call i8 @llvm.smax.i8(i8 [[X]], i8 42)
; CHECK-NEXT: ret i8 [[R]]
; CHECK-NEXT: [[TMP1:%.*]] = call i8 @llvm.umax.i8(i8 [[X]], i8 42)
; CHECK-NEXT: ret i8 [[TMP1]]
;
%lim = icmp sge i8 %x, 41
call void @llvm.assume(i1 %lim)
Expand Down Expand Up @@ -290,3 +290,68 @@ if.end:
%phi = phi i64 [%val, %bb1], [0, %entry]
ret i64 %phi
}

define i8 @test_smax_to_umax_nneg(i8 %a, i8 %b) {
; CHECK-LABEL: @test_smax_to_umax_nneg(
; CHECK-NEXT: [[NNEG_A:%.*]] = and i8 [[A:%.*]], 127
; CHECK-NEXT: [[NNEG_B:%.*]] = and i8 [[B:%.*]], 127
; CHECK-NEXT: [[TMP1:%.*]] = call i8 @llvm.umax.i8(i8 [[NNEG_A]], i8 [[NNEG_B]])
; CHECK-NEXT: ret i8 [[TMP1]]
;
%nneg_a = and i8 %a, 127
%nneg_b = and i8 %b, 127
%ret = call i8 @llvm.smax.i8(i8 %nneg_a, i8 %nneg_b)
ret i8 %ret
}

define i8 @test_smax_to_umax_neg(i8 %a, i8 %b) {
; CHECK-LABEL: @test_smax_to_umax_neg(
; CHECK-NEXT: [[NEG_A:%.*]] = or i8 [[A:%.*]], -128
; CHECK-NEXT: [[NEG_B:%.*]] = or i8 [[B:%.*]], -128
; CHECK-NEXT: [[TMP1:%.*]] = call i8 @llvm.umax.i8(i8 [[NEG_A]], i8 [[NEG_B]])
; CHECK-NEXT: ret i8 [[TMP1]]
;
%neg_a = or i8 %a, 128
%neg_b = or i8 %b, 128
%ret = call i8 @llvm.smax.i8(i8 %neg_a, i8 %neg_b)
ret i8 %ret
}

define i8 @test_smin_to_umin_nneg(i8 %a, i8 %b) {
; CHECK-LABEL: @test_smin_to_umin_nneg(
; CHECK-NEXT: [[NNEG_A:%.*]] = and i8 [[A:%.*]], 127
; CHECK-NEXT: [[NNEG_B:%.*]] = and i8 [[B:%.*]], 127
; CHECK-NEXT: [[TMP1:%.*]] = call i8 @llvm.umin.i8(i8 [[NNEG_A]], i8 [[NNEG_B]])
; CHECK-NEXT: ret i8 [[TMP1]]
;
%nneg_a = and i8 %a, 127
%nneg_b = and i8 %b, 127
%ret = call i8 @llvm.smin.i8(i8 %nneg_a, i8 %nneg_b)
ret i8 %ret
}

define i8 @test_smin_to_umin_neg(i8 %a, i8 %b) {
; CHECK-LABEL: @test_smin_to_umin_neg(
; CHECK-NEXT: [[NEG_A:%.*]] = or i8 [[A:%.*]], -128
; CHECK-NEXT: [[NEG_B:%.*]] = or i8 [[B:%.*]], -128
; CHECK-NEXT: [[TMP1:%.*]] = call i8 @llvm.umin.i8(i8 [[NEG_A]], i8 [[NEG_B]])
; CHECK-NEXT: ret i8 [[TMP1]]
;
%neg_a = or i8 %a, 128
%neg_b = or i8 %b, 128
%ret = call i8 @llvm.smin.i8(i8 %neg_a, i8 %neg_b)
ret i8 %ret
}

define i8 @test_umax_nneg(i8 %a, i8 %b) {
; CHECK-LABEL: @test_umax_nneg(
; CHECK-NEXT: [[NNEG_A:%.*]] = and i8 [[A:%.*]], 127
; CHECK-NEXT: [[NNEG_B:%.*]] = and i8 [[B:%.*]], 127
; CHECK-NEXT: [[RET:%.*]] = call i8 @llvm.umax.i8(i8 [[NNEG_A]], i8 [[NNEG_B]])
; CHECK-NEXT: ret i8 [[RET]]
;
%nneg_a = and i8 %a, 127
%nneg_b = and i8 %b, 127
%ret = call i8 @llvm.umax.i8(i8 %nneg_a, i8 %nneg_b)
ret i8 %ret
}
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