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[CVP] Use at-use info in processBinOp (#88523)

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This patch uses `getConstantRangeAtUse` to infer nsw/nuw flags with
at-use info. It will enables more optimizations in InstCombine.

Compile-time impact:
http://llvm-compile-time-tracker.com/compare.php?from=a5ed14bc8e122fa5ac0aa81f8d8390931bd6b4e4&to=a83d3402b663439b91cb37a046fb7ac0220ba5c7&stat=instructions%3Au

Related issue: #87854
This commit is contained in:
Yingwei Zheng 2024-04-13 15:07:55 +08:00 committed by GitHub
parent 3cf8535dbf
commit df9c00beea
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GPG Key ID: B5690EEEBB952194
3 changed files with 40 additions and 8 deletions
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11
llvm/lib/Transforms/Scalar/CorrelatedValuePropagation.cpp
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@ -1105,13 +1105,10 @@ static bool processBinOp(BinaryOperator *BinOp, LazyValueInfo *LVI) {
return false;
Instruction::BinaryOps Opcode = BinOp->getOpcode();
Value *LHS = BinOp->getOperand(0);
Value *RHS = BinOp->getOperand(1);
ConstantRange LRange =
LVI->getConstantRange(LHS, BinOp, /*UndefAllowed*/ false);
ConstantRange RRange =
LVI->getConstantRange(RHS, BinOp, /*UndefAllowed*/ false);
ConstantRange LRange = LVI->getConstantRangeAtUse(BinOp->getOperandUse(0),
/*UndefAllowed=*/false);
ConstantRange RRange = LVI->getConstantRangeAtUse(BinOp->getOperandUse(1),
/*UndefAllowed=*/false);
bool Changed = false;
bool NewNUW = false, NewNSW = false;

34
llvm/test/Transforms/CorrelatedValuePropagation/cond-at-use.ll
View File

@ -596,3 +596,37 @@ define i16 @and_elide_poison_flags_missing_noundef(i16 %a) {
%sel = select i1 %cmp, i16 %and, i16 24
ret i16 %sel
}
define i32 @pr87854(i32 noundef %x.1, i32 noundef %i) {
; CHECK-LABEL: @pr87854(
; CHECK-NEXT: [[COND:%.*]] = icmp sgt i32 [[X_1:%.*]], -1
; CHECK-NEXT: tail call void @llvm.assume(i1 [[COND]])
; CHECK-NEXT: [[INBOUNDS:%.*]] = icmp ult i32 [[I:%.*]], [[X_1]]
; CHECK-NEXT: [[NEXT:%.*]] = add nuw i32 [[I]], 1
; CHECK-NEXT: [[SPEC_SELECT:%.*]] = select i1 [[INBOUNDS]], i32 [[NEXT]], i32 -1
; CHECK-NEXT: ret i32 [[SPEC_SELECT]]
;
%cond = icmp sgt i32 %x.1, -1
tail call void @llvm.assume(i1 %cond)
%inbounds = icmp ult i32 %i, %x.1
%next = add i32 %i, 1
%spec.select = select i1 %inbounds, i32 %next, i32 -1
ret i32 %spec.select
}
define i64 @test_shl_nsw_at_use(i64 noundef %x) {
; CHECK-LABEL: @test_shl_nsw_at_use(
; CHECK-NEXT: [[ADD:%.*]] = add i64 [[X:%.*]], 2147483648
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i64 [[ADD]], 4294967296
; CHECK-NEXT: [[SHL:%.*]] = shl nsw i64 [[X]], 32
; CHECK-NEXT: [[SHR:%.*]] = ashr exact i64 [[SHL]], 32
; CHECK-NEXT: [[RES:%.*]] = select i1 [[CMP]], i64 [[SHR]], i64 0
; CHECK-NEXT: ret i64 [[RES]]
;
%add = add i64 %x, 2147483648
%cmp = icmp ult i64 %add, 4294967296
%shl = shl i64 %x, 32
%shr = ashr exact i64 %shl, 32
%res = select i1 %cmp, i64 %shr, i64 0
ret i64 %res
}

3
llvm/test/Transforms/CorrelatedValuePropagation/phi-common-val.ll
View File

@ -156,12 +156,13 @@ bb3:
define i32 @PR43802_without_nowrap(i32 %arg) {
; CHECK-LABEL: @PR43802_without_nowrap(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[SUB:%.*]] = sub i32 0, [[ARG:%.*]]
; CHECK-NEXT: [[SUB1:%.*]] = sub nsw i32 0, [[ARG:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[ARG]], -2147483648
; CHECK-NEXT: br i1 [[CMP]], label [[BB2:%.*]], label [[BB3:%.*]]
; CHECK: bb2:
; CHECK-NEXT: br label [[BB3]]
; CHECK: bb3:
; CHECK-NEXT: [[SUB:%.*]] = phi i32 [ -2147483648, [[BB2]] ], [ [[SUB1]], [[ENTRY:%.*]] ]
; CHECK-NEXT: ret i32 [[SUB]]
;
entry: