maxjhandsome
/
llvm-project
forked from OSchip/llvm-project
1
0
Fork 0
Code Issues Pull Requests Packages Releases Wiki Activity

[indvars] Extend canonicalizeExitConditions to inverted operands 

As discussed in the original reviews, but done in a follow on.
This commit is contained in:
Philip Reames 2021-11-04 14:19:24 -07:00
parent eb0fa8bfa3
commit 453fdebd48
2 changed files with 21 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
llvm/lib/Transforms/Scalar/IndVarSimplify.cpp
View File

@ -1439,8 +1439,12 @@ bool IndVarSimplify::canonicalizeExitCondition(Loop *L) {
// For the range reasoning, avoid computing SCEVs in the loop to avoid
// poisoning cache with sub-optimal results. For the must-execute case,
// this is a neccessary precondition for correctness.
if (!L->isLoopInvariant(RHS))
continue;
if (!L->isLoopInvariant(RHS)) {
if (!L->isLoopInvariant(LHS))
continue;
// Same logic applies for the inverse case
std::swap(LHS, RHS);
}
// Match (icmp signed-cond zext, RHS)
Value *LHSOp = nullptr;
@ -1475,11 +1479,19 @@ bool IndVarSimplify::canonicalizeExitCondition(Loop *L) {
if (!ICmp || !ICmp->hasOneUse() || !ICmp->isUnsigned())
continue;
bool Swapped = false;
auto *LHS = ICmp->getOperand(0);
auto *RHS = ICmp->getOperand(1);
if (L->isLoopInvariant(LHS) || !L->isLoopInvariant(RHS))
if (L->isLoopInvariant(LHS) == L->isLoopInvariant(RHS))
// Nothing to rotate
continue;
if (L->isLoopInvariant(LHS)) {
// Same logic applies for the inverse case until we actually pick
// which operand of the compare to update.
Swapped = true;
std::swap(LHS, RHS);
}
assert(!L->isLoopInvariant(LHS) && L->isLoopInvariant(RHS));
if (!LHS->hasOneUse())
// Can't rotate without increasing instruction count
@ -1501,8 +1513,8 @@ bool IndVarSimplify::canonicalizeExitCondition(Loop *L) {
auto *NewRHS =
CastInst::Create(Instruction::Trunc, RHS, LHSOp->getType(), "",
L->getLoopPreheader()->getTerminator());
ICmp->setOperand(0, LHSOp);
ICmp->setOperand(1, NewRHS);
ICmp->setOperand(Swapped ? 1 : 0, LHSOp);
ICmp->setOperand(Swapped ? 0 : 1, NewRHS);
if (LHS->use_empty())
DeadInsts.push_back(LHS);
};

8
llvm/test/Transforms/IndVarSimplify/finite-exit-comparisons.ll
View File

@ -824,12 +824,12 @@ for.end: ; preds = %for.body, %entry
define void @slt_constant_lhs(i16 %n.raw, i8 %start) mustprogress {
; CHECK-LABEL: @slt_constant_lhs(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = trunc i16 254 to i8
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ [[START:%.*]], [[ENTRY:%.*]] ]
; CHECK-NEXT: [[IV_NEXT]] = add i8 [[IV]], 1
; CHECK-NEXT: [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i16 254, [[ZEXT]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i8 [[TMP0]], [[IV_NEXT]]
; CHECK-NEXT: br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
; CHECK: for.end:
; CHECK-NEXT: ret void
@ -878,12 +878,12 @@ for.end: ; preds = %for.body, %entry
define void @ult_constant_lhs(i16 %n.raw, i8 %start) mustprogress {
; CHECK-LABEL: @ult_constant_lhs(
; CHECK-NEXT: entry:
; CHECK-NEXT: [[TMP0:%.*]] = trunc i16 254 to i8
; CHECK-NEXT: br label [[FOR_BODY:%.*]]
; CHECK: for.body:
; CHECK-NEXT: [[IV:%.*]] = phi i8 [ [[IV_NEXT:%.*]], [[FOR_BODY]] ], [ [[START:%.*]], [[ENTRY:%.*]] ]
; CHECK-NEXT: [[IV_NEXT]] = add i8 [[IV]], 1
; CHECK-NEXT: [[ZEXT:%.*]] = zext i8 [[IV_NEXT]] to i16
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i16 254, [[ZEXT]]
; CHECK-NEXT: [[CMP:%.*]] = icmp ult i8 [[TMP0]], [[IV_NEXT]]
; CHECK-NEXT: br i1 [[CMP]], label [[FOR_BODY]], label [[FOR_END:%.*]]
; CHECK: for.end:
; CHECK-NEXT: ret void