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[LoopReroll] Relax some assumptions a little.

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We won't find a root with index zero in any loop that we are able to reroll.
However, we may find one in a non-rerollable loop, so bail gracefully instead
of failing hard.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@229406 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
James Molloy 2015-02-16 17:02:00 +00:00
parent 4b739069e4
commit 2a7fbb1927
2 changed files with 36 additions and 3 deletions
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9
lib/Transforms/Scalar/LoopRerollPass.cpp
View File

@ -719,14 +719,17 @@ collectPossibleRoots(Instruction *Base, std::map<int64_t,Instruction*> &Roots) {
if (Roots.empty())
return false;
assert(Roots.find(0) == Roots.end() && "Didn't expect a zero index!");
// If we found non-loop-inc, non-root users of Base, assume they are
// for the zeroth root index. This is because "add %a, 0" gets optimized
// away.
if (BaseUsers.size())
if (BaseUsers.size()) {
if (Roots.find(0) != Roots.end()) {
DEBUG(dbgs() << "LRR: Multiple roots found for base - aborting!\n");
return false;
}
Roots[0] = Base;
}
// Calculate the number of users of the base, or lowest indexed, iteration.
unsigned NumBaseUses = BaseUsers.size();

30
test/Transforms/LoopReroll/basic.ll
View File

@ -545,6 +545,36 @@ for.end: ; preds = %for.body
ret void
}
%struct.s = type { i32, i32 }
; Function Attrs: nounwind uwtable
define void @gep1(%struct.s* nocapture %x) #0 {
entry:
%call = tail call i32 @foo(i32 0) #1
br label %for.body
for.body: ; preds = %for.body, %entry
%indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
%0 = mul nsw i64 %indvars.iv, 3
%arrayidx = getelementptr inbounds %struct.s* %x, i64 %0, i32 0
store i32 %call, i32* %arrayidx, align 4
%1 = add nsw i64 %0, 1
%arrayidx4 = getelementptr inbounds %struct.s* %x, i64 %1, i32 0
store i32 %call, i32* %arrayidx4, align 4
%2 = add nsw i64 %0, 2
%arrayidx9 = getelementptr inbounds %struct.s* %x, i64 %2, i32 0
store i32 %call, i32* %arrayidx9, align 4
%indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
%exitcond = icmp eq i64 %indvars.iv.next, 500
br i1 %exitcond, label %for.end, label %for.body
; CHECK-LABEL: @gep1
; This test is a crash test only.
; CHECK: ret
for.end: ; preds = %for.body
ret void
}
attributes #0 = { nounwind uwtable }
attributes #1 = { nounwind }