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[SCCP] [Transform] Adding ICMP folding for zext and sext in SCCPSolver #67594

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[SCCP] [Transform] Adding ICMP folding for zext and sext in SCCPSolver #67594

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399f9d6
Adding ICMP folding for SCCPSolver
leo-ard Sep 27, 2023
6e972aa
Format SCCPSolver according to clang-format
leo-ard Sep 27, 2023
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19 changes: 19 additions & 0 deletions clang/test/CodeGen/X86/min_max.c
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@@ -0,0 +1,19 @@
// RUN: %clang_cc1 %s -O2 -triple=x86_64-apple-darwin -emit-llvm -o - | FileCheck %s

short vecreduce_smax_v2i16(int n, short* v)
{
// CHECK: @llvm.smax
short p = 0;
for (int i = 0; i < n; ++i)
p = p < v[i] ? v[i] : p;
return p;
}

short vecreduce_smin_v2i16(int n, short* v)
{
// CHECK: @llvm.smin
short p = 0;
for (int i = 0; i < n; ++i)
p = p > v[i] ? v[i] : p;
return p;
}
60 changes: 60 additions & 0 deletions llvm/lib/Transforms/Utils/SCCPSolver.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -193,6 +193,66 @@ static bool replaceSignedInst(SCCPSolver &Solver,
NewInst = BinaryOperator::Create(NewOpcode, Op0, Op1, "", &Inst);
break;
}
case Instruction::ICmp: {
ICmpInst &ICmp = cast<ICmpInst>(Inst);

ZExtInst *Op0_zext = dyn_cast<ZExtInst>(ICmp.getOperand(0));
SExtInst *Op0_sext = dyn_cast<SExtInst>(ICmp.getOperand(0));

ZExtInst *Op1_zext = dyn_cast<ZExtInst>(ICmp.getOperand(1));
SExtInst *Op1_sext = dyn_cast<SExtInst>(ICmp.getOperand(1));

CastInst *Op0;
CastInst *Op1;

if (Op0_zext)
Op0 = Op0_zext;
else
Op0 = Op0_sext;
if (Op1_zext)
Op1 = Op1_zext;
else
Op1 = Op1_sext;

bool reversed = false;

if (!Op0 || !Op1) {
// Op0 and Op1 must be defined
return false;
}

if (Op1_zext && (!Op0_zext)) {
// We force Op0 to be a zext and reverse the arguments
// at the end if we swap
reversed = true;
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IMHO the swapping makes it harder to read. Not swapping would force case to be checked in the if statement, but would make the code more readable.


std::swap(Op0_zext, Op1_zext);
std::swap(Op0_sext, Op1_sext);
std::swap(Op0, Op1);
}

if (Op0->getType() != Op1->getType()) {
// extensions are not of the same type
// This optimization is done in InstCombine
return false;
}

// ICMP (sext X) (sext y) => ICMP X, Y
// ICMP (zext X) (zext y) => ICMP X, Y
// ICMP (zext X) (sext Y) => ICMP X, Y if X >= 0 and ICMP signed
if ((Op0_zext && Op1_zext) || (Op0_sext && Op1_sext) ||
(ICmp.isSigned() && Op0_zext && Op1_sext &&
isNonNegative(Op0_zext->getOperand(0)))) {

Value *X = Op0->getOperand(0);
Value *Y = Op1->getOperand(0);
NewInst = CmpInst::Create(ICmp.getOpcode(), ICmp.getPredicate(),
reversed ? Y : X, reversed ? X : Y, "", &Inst);
break;
}

return false;
}
default:
return false;
}
Expand Down
185 changes: 185 additions & 0 deletions llvm/test/Transforms/SCCP/icmp-fold-with-cast.ll
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@@ -0,0 +1,185 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --tool ./bin/opt --version 3
; See PRXXX for more details
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See PRXXX Was that autogenerated ? Does it need to be updated ?

; RUN: opt < %s -S -passes=ipsccp | FileCheck %s


define signext i32 @sext_sext(i16 %x, i16 %y) {
; CHECK-LABEL: define signext i32 @sext_sext(
; CHECK-SAME: i16 [[X:%.*]], i16 [[Y:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CONV:%.*]] = sext i16 [[X]] to i32
; CHECK-NEXT: [[CONV1:%.*]] = sext i16 [[Y]] to i32
; CHECK-NEXT: [[CMP2:%.*]] = icmp sgt i16 [[X]], [[Y]]
; CHECK-NEXT: br i1 [[CMP2]], label [[COND_TRUE:%.*]], label [[COND_FALSE:%.*]]
; CHECK: cond.true:
; CHECK-NEXT: br label [[COND_END:%.*]]
; CHECK: cond.false:
; CHECK-NEXT: br label [[COND_END]]
; CHECK: cond.end:
; CHECK-NEXT: [[COND:%.*]] = phi i32 [ 0, [[COND_TRUE]] ], [ 1, [[COND_FALSE]] ]
; CHECK-NEXT: ret i32 [[COND]]
;
entry:
%conv = sext i16 %x to i32
%conv1 = sext i16 %y to i32
%cmp2 = icmp sgt i32 %conv, %conv1
br i1 %cmp2, label %cond.true, label %cond.false

cond.true: ; preds = %for.body
br label %cond.end

cond.false: ; preds = %for.body
br label %cond.end

cond.end: ; preds = %cond.false, %cond.true
%cond = phi i32 [ 0, %cond.true ], [ 1, %cond.false ]
ret i32 %cond
}


define signext i32 @zext_zext(i16 %x, i16 %y) {
; CHECK-LABEL: define signext i32 @zext_zext(
; CHECK-SAME: i16 [[X:%.*]], i16 [[Y:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: [[CONV:%.*]] = zext i16 [[X]] to i32
; CHECK-NEXT: [[CONV1:%.*]] = zext i16 [[Y]] to i32
; CHECK-NEXT: [[CMP2:%.*]] = icmp sgt i16 [[X]], [[Y]]
; CHECK-NEXT: br i1 [[CMP2]], label [[COND_TRUE:%.*]], label [[COND_FALSE:%.*]]
; CHECK: cond.true:
; CHECK-NEXT: br label [[COND_END:%.*]]
; CHECK: cond.false:
; CHECK-NEXT: br label [[COND_END]]
; CHECK: cond.end:
; CHECK-NEXT: [[COND:%.*]] = phi i32 [ 0, [[COND_TRUE]] ], [ 1, [[COND_FALSE]] ]
; CHECK-NEXT: ret i32 [[COND]]
;
entry:
%conv = zext i16 %x to i32
%conv1 = zext i16 %y to i32
%cmp2 = icmp sgt i32 %conv, %conv1
br i1 %cmp2, label %cond.true, label %cond.false

cond.true: ; preds = %for.body
br label %cond.end

cond.false: ; preds = %for.body
br label %cond.end

cond.end: ; preds = %cond.false, %cond.true
%cond = phi i32 [ 0, %cond.true ], [ 1, %cond.false ]
ret i32 %cond
}


define signext i16 @zext_positive_and_sext(i32 noundef %n, ptr noundef %v) {
; CHECK-LABEL: define signext i16 @zext_positive_and_sext(
; CHECK-SAME: i32 noundef [[N:%.*]], ptr noundef [[V:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[FOR_COND:%.*]]
; CHECK: for.cond:
; CHECK-NEXT: [[P_0:%.*]] = phi i16 [ 0, [[ENTRY:%.*]] ], [ [[CONV8:%.*]], [[COND_END:%.*]] ]
; CHECK-NEXT: [[I_0:%.*]] = phi i32 [ 0, [[ENTRY]] ], [ [[INC:%.*]], [[COND_END]] ]
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[I_0]], [[N]]
; CHECK-NEXT: br i1 [[CMP]], label [[FOR_BODY:%.*]], label [[FOR_COND_CLEANUP:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[CONV:%.*]] = zext i16 [[P_0]] to i32
; CHECK-NEXT: [[IDXPROM:%.*]] = sext i32 [[I_0]] to i64
; CHECK-NEXT: [[ARRAYIDX:%.*]] = getelementptr i16, ptr [[V]], i64 [[IDXPROM]]
; CHECK-NEXT: [[TMP0:%.*]] = load i16, ptr [[ARRAYIDX]], align 2
; CHECK-NEXT: [[CONV1:%.*]] = sext i16 [[TMP0]] to i32
; CHECK-NEXT: [[CMP2:%.*]] = icmp slt i16 [[P_0]], [[TMP0]]
; CHECK-NEXT: br i1 [[CMP2]], label [[COND_TRUE:%.*]], label [[COND_FALSE:%.*]]
; CHECK: cond.true:
; CHECK-NEXT: br label [[COND_END]]
; CHECK: cond.false:
; CHECK-NEXT: br label [[COND_END]]
; CHECK: for.cond.cleanup:
; CHECK-NEXT: ret i16 [[P_0]]
; CHECK: cond.end:
; CHECK-NEXT: [[COND:%.*]] = phi i32 [ [[CONV1]], [[COND_TRUE]] ], [ [[CONV]], [[COND_FALSE]] ]
; CHECK-NEXT: [[CONV8]] = trunc i32 [[COND]] to i16
; CHECK-NEXT: [[INC]] = add nsw i32 [[I_0]], 1
; CHECK-NEXT: br label [[FOR_COND]]
;
entry:
br label %for.cond

for.cond: ; preds = %cond.end, %entry
%p.0 = phi i16 [ 0, %entry ], [ %conv8, %cond.end ]
%i.0 = phi i32 [ 0, %entry ], [ %inc, %cond.end ]
%cmp = icmp slt i32 %i.0, %n
br i1 %cmp, label %for.body, label %for.cond.cleanup

for.body: ; preds = %for.cond
%conv = zext i16 %p.0 to i32 ;; %p.0 is always positive here
%idxprom = sext i32 %i.0 to i64
%arrayidx = getelementptr i16, ptr %v, i64 %idxprom
%0 = load i16, ptr %arrayidx, align 2
%conv1 = sext i16 %0 to i32
%cmp2 = icmp slt i32 %conv, %conv1
br i1 %cmp2, label %cond.true, label %cond.false

cond.true: ; preds = %for.body
br label %cond.end

cond.false: ; preds = %for.body
br label %cond.end

for.cond.cleanup: ; preds = %for.cond
ret i16 %p.0

cond.end: ; preds = %cond.false, %cond.true
%cond = phi i32 [ %conv1, %cond.true ], [ %conv, %cond.false ]
%conv8 = trunc i32 %cond to i16
%inc = add nsw i32 %i.0, 1
br label %for.cond
}



define signext i16 @sext_and_zext_positive(i16 %x) {
; CHECK-LABEL: define signext i16 @sext_and_zext_positive(
; CHECK-SAME: i16 [[X:%.*]]) {
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[FOR_COND:%.*]]
; CHECK: for.cond:
; CHECK-NEXT: [[V:%.*]] = phi i16 [ 0, [[ENTRY:%.*]] ], [ [[INC:%.*]], [[COND_END:%.*]] ]
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[CONV:%.*]] = zext i16 [[V]] to i32
; CHECK-NEXT: [[CONV1:%.*]] = sext i16 [[X]] to i32
; CHECK-NEXT: [[CMP2:%.*]] = icmp slt i16 [[X]], [[V]]
; CHECK-NEXT: br i1 [[CMP2]], label [[COND_TRUE:%.*]], label [[COND_FALSE:%.*]]
; CHECK: cond.true:
; CHECK-NEXT: br label [[COND_END]]
; CHECK: cond.false:
; CHECK-NEXT: br label [[COND_END]]
; CHECK: cond.end:
; CHECK-NEXT: [[A:%.*]] = phi i16 [ 10, [[COND_TRUE]] ], [ 20, [[COND_FALSE]] ]
; CHECK-NEXT: [[INC]] = add nuw nsw i16 [[A]], 1
; CHECK-NEXT: br label [[FOR_COND]]
;
entry:
br label %for.cond

for.cond: ; preds = %cond.end, %entry
%v = phi i16 [ 0, %entry ], [ %inc, %cond.end ] ;; always positive
br label %for.body

for.body: ; preds = %for.cond
%conv = zext i16 %v to i32 ;; %p.0 is always positive here
%conv1 = sext i16 %x to i32 ;; %p.0 is always positive here
%cmp2 = icmp slt i32 %conv1, %conv ;; positive/positive
br i1 %cmp2, label %cond.true, label %cond.false

cond.true: ; preds = %for.body
br label %cond.end

cond.false: ; preds = %for.body
br label %cond.end

cond.end: ; preds = %cond.false, %cond.true
%a = phi i16 [ 10, %cond.true ], [ 20, %cond.false ]
%inc = add i16 %a, 1
br label %for.cond
}
4 changes: 2 additions & 2 deletions llvm/test/Transforms/SCCP/widening.ll
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Expand Up @@ -653,7 +653,7 @@ define ptr @wobble(ptr %arg, i32 %arg1) align 2 {
; SCCP-NEXT: [[TMP52:%.*]] = call dereferenceable(1) ptr @spam(ptr [[ARG]], i32 [[TMP51]])
; SCCP-NEXT: [[TMP53:%.*]] = load i8, ptr [[TMP52]], align 1
; SCCP-NEXT: [[TMP54:%.*]] = zext i8 [[TMP53]] to i32
; SCCP-NEXT: [[TMP55:%.*]] = icmp sgt i32 [[TMP48]], [[TMP54]]
; SCCP-NEXT: [[TMP55:%.*]] = icmp sgt i8 [[TMP47]], [[TMP53]]
; SCCP-NEXT: br i1 [[TMP55]], label [[BB56:%.*]], label [[BB60:%.*]]
; SCCP: bb56:
; SCCP-NEXT: [[TMP57:%.*]] = add nsw i32 [[TMP40]], -1
Expand Down Expand Up @@ -734,7 +734,7 @@ define ptr @wobble(ptr %arg, i32 %arg1) align 2 {
; IPSCCP-NEXT: [[TMP52:%.*]] = call dereferenceable(1) ptr @spam(ptr [[ARG]], i32 [[TMP51]])
; IPSCCP-NEXT: [[TMP53:%.*]] = load i8, ptr [[TMP52]], align 1
; IPSCCP-NEXT: [[TMP54:%.*]] = zext i8 [[TMP53]] to i32
; IPSCCP-NEXT: [[TMP55:%.*]] = icmp sgt i32 [[TMP48]], [[TMP54]]
; IPSCCP-NEXT: [[TMP55:%.*]] = icmp sgt i8 [[TMP47]], [[TMP53]]
; IPSCCP-NEXT: br i1 [[TMP55]], label [[BB56:%.*]], label [[BB60:%.*]]
; IPSCCP: bb56:
; IPSCCP-NEXT: br label [[BB60]]
Expand Down