forked from OSchip/llvm-project
Tweak IVUsers' concept of "interesting" to exclude add recurrences
where the step value is an induction variable from an outer loop, to avoid trouble trying to re-expand such expressions. This effectively hides such expressions from indvars and lsr, which prevents them from getting into trouble. llvm-svn: 111317
This commit is contained in:
parent
dd0087154a
commit
ed2b005842
|
@ -38,27 +38,31 @@ Pass *llvm::createIVUsersPass() {
|
|||
/// isInteresting - Test whether the given expression is "interesting" when
|
||||
/// used by the given expression, within the context of analyzing the
|
||||
/// given loop.
|
||||
static bool isInteresting(const SCEV *S, const Instruction *I, const Loop *L) {
|
||||
// Anything loop-invariant is interesting.
|
||||
if (!isa<SCEVUnknown>(S) && S->isLoopInvariant(L))
|
||||
return true;
|
||||
|
||||
static bool isInteresting(const SCEV *S, const Instruction *I, const Loop *L,
|
||||
ScalarEvolution *SE) {
|
||||
// An addrec is interesting if it's affine or if it has an interesting start.
|
||||
if (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(S)) {
|
||||
// Keep things simple. Don't touch loop-variant strides.
|
||||
if (AR->getLoop() == L)
|
||||
return AR->isAffine() || !L->contains(I);
|
||||
// Otherwise recurse to see if the start value is interesting.
|
||||
return isInteresting(AR->getStart(), I, L);
|
||||
// Otherwise recurse to see if the start value is interesting, and that
|
||||
// the step value is not interesting, since we don't yet know how to
|
||||
// do effective SCEV expansions for addrecs with interesting steps.
|
||||
return isInteresting(AR->getStart(), I, L, SE) &&
|
||||
!isInteresting(AR->getStepRecurrence(*SE), I, L, SE);
|
||||
}
|
||||
|
||||
// An add is interesting if any of its operands is.
|
||||
// An add is interesting if exactly one of its operands is interesting.
|
||||
if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S)) {
|
||||
bool AnyInterestingYet = false;
|
||||
for (SCEVAddExpr::op_iterator OI = Add->op_begin(), OE = Add->op_end();
|
||||
OI != OE; ++OI)
|
||||
if (isInteresting(*OI, I, L))
|
||||
return true;
|
||||
return false;
|
||||
if (isInteresting(*OI, I, L, SE)) {
|
||||
if (AnyInterestingYet)
|
||||
return false;
|
||||
AnyInterestingYet = true;
|
||||
}
|
||||
return AnyInterestingYet;
|
||||
}
|
||||
|
||||
// Nothing else is interesting here.
|
||||
|
@ -84,7 +88,7 @@ bool IVUsers::AddUsersIfInteresting(Instruction *I) {
|
|||
|
||||
// If we've come to an uninteresting expression, stop the traversal and
|
||||
// call this a user.
|
||||
if (!isInteresting(ISE, I, L))
|
||||
if (!isInteresting(ISE, I, L, SE))
|
||||
return false;
|
||||
|
||||
SmallPtrSet<Instruction *, 4> UniqueUsers;
|
||||
|
|
|
@ -1,4 +1,4 @@
|
|||
; RUN: llc -mtriple=x86_64-apple-darwin -march=x86-64 < %s -stats -info-output-file - | grep machine-licm | grep 2
|
||||
; RUN: llc -mtriple=x86_64-apple-darwin -march=x86-64 < %s -stats -info-output-file - | grep machine-licm | grep 3
|
||||
|
||||
; MachineLICM should be able to hoist the symbolic addresses out of
|
||||
; the inner loops.
|
||||
|
|
|
@ -0,0 +1,51 @@
|
|||
; RUN: llc < %s -march=x86-64 -relocation-model=static -mtriple=x86_64-unknown-linux-gnu
|
||||
|
||||
; The inner loop should require only one add (and no leas either).
|
||||
; rdar://8100380
|
||||
|
||||
; CHECK: BB0_4:
|
||||
; CHECK-NEXT: movb $0, flags(%rdx)
|
||||
; CHECK-NEXT: addq %rcx, %rdx
|
||||
; CHECK-NEXT: cmpq $8192, %rdx
|
||||
; CHECK-NEXT: jl
|
||||
|
||||
@flags = external global [8192 x i8], align 16 ; <[8192 x i8]*> [#uses=1]
|
||||
|
||||
define void @foo() nounwind {
|
||||
entry:
|
||||
%tmp = icmp slt i64 2, 8192 ; <i1> [#uses=1]
|
||||
br i1 %tmp, label %bb, label %bb21
|
||||
|
||||
bb: ; preds = %entry
|
||||
br label %bb7
|
||||
|
||||
bb7: ; preds = %bb, %bb17
|
||||
%tmp8 = phi i64 [ %tmp18, %bb17 ], [ 2, %bb ] ; <i64> [#uses=2]
|
||||
%tmp9 = icmp slt i64 2, 8192 ; <i1> [#uses=1]
|
||||
br i1 %tmp9, label %bb10, label %bb17
|
||||
|
||||
bb10: ; preds = %bb7
|
||||
br label %bb11
|
||||
|
||||
bb11: ; preds = %bb10, %bb11
|
||||
%tmp12 = phi i64 [ %tmp14, %bb11 ], [ 2, %bb10 ] ; <i64> [#uses=2]
|
||||
%tmp13 = getelementptr inbounds [8192 x i8]* @flags, i64 0, i64 %tmp12 ; <i8*> [#uses=1]
|
||||
store i8 0, i8* %tmp13, align 1
|
||||
%tmp14 = add nsw i64 %tmp12, %tmp8 ; <i64> [#uses=2]
|
||||
%tmp15 = icmp slt i64 %tmp14, 8192 ; <i1> [#uses=1]
|
||||
br i1 %tmp15, label %bb11, label %bb16
|
||||
|
||||
bb16: ; preds = %bb11
|
||||
br label %bb17
|
||||
|
||||
bb17: ; preds = %bb16, %bb7
|
||||
%tmp18 = add nsw i64 %tmp8, 1 ; <i64> [#uses=2]
|
||||
%tmp19 = icmp slt i64 %tmp18, 8192 ; <i1> [#uses=1]
|
||||
br i1 %tmp19, label %bb7, label %bb20
|
||||
|
||||
bb20: ; preds = %bb17
|
||||
br label %bb21
|
||||
|
||||
bb21: ; preds = %bb20, %entry
|
||||
ret void
|
||||
}
|
Loading…
Reference in New Issue