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[LoopUnroll] Properly update loop structure in case of successful peeling. 

When peeling kicks in, it updates the loop preheader.
Later, a successful full unroll of the loop needs to update a PHI
which i-th argument comes from the loop preheader, so it'd better look
at the correct block. Fixes PR33437.

Differential Revision:  https://reviews.llvm.org/D37153

llvm-svn: 311922
This commit is contained in:
Davide Italiano 2017-08-28 20:29:33 +00:00
parent 0f76a35c5e
commit 20cb7e887f
2 changed files with 43 additions and 2 deletions
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15
llvm/lib/Transforms/Utils/LoopUnroll.cpp
View File

@ -396,8 +396,19 @@ bool llvm::UnrollLoop(Loop *L, unsigned Count, unsigned TripCount, bool Force,
"Did not expect runtime trip-count unrolling "
"and peeling for the same loop");
if (PeelCount)
peelLoop(L, PeelCount, LI, SE, DT, AC, PreserveLCSSA);
if (PeelCount) {
bool Peeled = peelLoop(L, PeelCount, LI, SE, DT, AC, PreserveLCSSA);
// Successful peeling may result in a change in the loop preheader/trip
// counts. If we later unroll the loop, we want these to be updated.
if (Peeled) {
BasicBlock *ExitingBlock = L->getExitingBlock();
assert(ExitingBlock && "Loop without exiting block?");
Preheader = L->getLoopPreheader();
TripCount = SE->getSmallConstantTripCount(L, ExitingBlock);
TripMultiple = SE->getSmallConstantTripMultiple(L, ExitingBlock);
}
}
// Loops containing convergent instructions must have a count that divides
// their TripMultiple.

30
llvm/test/Transforms/LoopUnroll/pr33437.ll Normal file
View File

@ -0,0 +1,30 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -loop-unroll %s -S | FileCheck %s
declare zeroext i8 @patatino()
define fastcc void @tinky() {
; CHECK-LABEL: @tinky(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[FOR_COND93:%.*]]
; CHECK: for.cond93:
; CHECK-NEXT: br label [[FOR_BODY198:%.*]]
; CHECK: for.body198:
; CHECK-NEXT: [[CALL593:%.*]] = tail call zeroext i8 @patatino()
; CHECK-NEXT: ret void
;
entry:
br label %for.cond93
for.cond93.loopexit:
ret void
for.cond93:
br label %for.body198
for.body198:
%l_249.12 = phi i8 [ undef, %for.cond93 ], [ %call593, %for.body198 ]
%l_522.01 = phi i32 [ 0, %for.cond93 ], [ 1, %for.body198 ]
%call593 = tail call zeroext i8 @patatino()
br i1 false, label %for.body198, label %for.cond93.loopexit
}