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LSR fix: broaden the check for loop preheaders.

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It's becoming clear that LoopSimplify needs to unconditionally create loop preheaders. But that is a bigger fix. For now, continuing to hack LSR.
Fixes rdar://10701050 "Cannot split an edge from an IndirectBrInst" assert.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@148288 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Andrew Trick 2012-01-17 06:45:52 +00:00
parent 37c2677fbc
commit 0f080913d1
2 changed files with 126 additions and 5 deletions
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18
lib/Transforms/Scalar/LoopStrengthReduce.cpp
View File

@ -4518,11 +4518,19 @@ LSRInstance::LSRInstance(const TargetLowering *tli, Loop *l, Pass *P)
if (!L->isLoopSimplifyForm())
return;
// All outer loops must have preheaders, or SCEVExpander may not be able to
// materialize an AddRecExpr whose Start is an outer AddRecExpr.
for (const Loop *OuterLoop = L; (OuterLoop = OuterLoop->getParentLoop());) {
if (!OuterLoop->getLoopPreheader())
return;
// All dominating loops must have preheaders, or SCEVExpander may not be able
// to materialize an AddRecExpr whose Start is an outer AddRecExpr.
//
// FIXME: This is a little absurd. I think LoopSimplify should be taught
// to create a preheader under any circumstance.
for (DomTreeNode *Rung = DT.getNode(L->getLoopPreheader());
Rung; Rung = Rung->getIDom()) {
BasicBlock *BB = Rung->getBlock();
const Loop *DomLoop = LI.getLoopFor(BB);
if (DomLoop && DomLoop->getHeader() == BB) {
if (!DomLoop->getLoopPreheader())
return;
}
}
// If there's no interesting work to be done, bail early.
if (IU.empty()) return;

113
test/Transforms/LoopStrengthReduce/2012-01-16-nopreheader.ll Normal file
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@ -0,0 +1,113 @@
; RUN: opt -loop-reduce -S < %s | FileCheck %s
;
; <rdar://10701050> "Cannot split an edge from an IndirectBrInst" assert.
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
target triple = "x86_64-apple-darwin10.0.0"
; while.cond197 is a dominates the simplified loop while.cond238 but
; has no with no preheader.
;
; CHECK: @nopreheader
; CHECK: %while.cond238
; CHECK: phi i64
; CHECK-NOT: phi
; CHECK: indirectbr
define void @nopreheader(i8* %end) nounwind {
entry:
br label %while.cond179
while.cond179: ; preds = %if.end434, %if.end369, %if.end277, %if.end165
%s.1 = phi i8* [ undef, %if.end434 ], [ %incdec.ptr356, %if.end348 ], [ undef, %entry ]
indirectbr i8* undef, [label %land.rhs184, label %while.end453]
land.rhs184: ; preds = %while.cond179
indirectbr i8* undef, [label %while.end453, label %while.cond197]
while.cond197: ; preds = %land.rhs202, %land.rhs184
%0 = phi i64 [ %indvar.next11, %land.rhs202 ], [ 0, %land.rhs184 ]
indirectbr i8* undef, [label %land.rhs202, label %while.end215]
land.rhs202: ; preds = %while.cond197
%indvar.next11 = add i64 %0, 1
indirectbr i8* undef, [label %while.end215, label %while.cond197]
while.end215: ; preds = %land.rhs202, %while.cond197
indirectbr i8* undef, [label %PREMATURE, label %if.end221]
if.end221: ; preds = %while.end215
indirectbr i8* undef, [label %while.cond238.preheader, label %lor.lhs.false227]
lor.lhs.false227: ; preds = %if.end221
indirectbr i8* undef, [label %while.cond238.preheader, label %if.else]
while.cond238.preheader: ; preds = %lor.lhs.false227, %if.end221
%tmp16 = add i64 %0, 2
indirectbr i8* undef, [label %while.cond238]
while.cond238: ; preds = %land.rhs243, %while.cond238.preheader
%1 = phi i64 [ %indvar.next15, %land.rhs243 ], [ 0, %while.cond238.preheader ]
%tmp36 = add i64 %tmp16, %1
%s.3 = getelementptr i8* %s.1, i64 %tmp36
%cmp241 = icmp ult i8* %s.3, %end
indirectbr i8* undef, [label %land.rhs243, label %while.end256]
land.rhs243: ; preds = %while.cond238
%indvar.next15 = add i64 %1, 1
indirectbr i8* undef, [label %while.end256, label %while.cond238]
while.end256: ; preds = %land.rhs243, %while.cond238
indirectbr i8* undef, [label %PREMATURE]
if.else: ; preds = %lor.lhs.false227
indirectbr i8* undef, [label %if.then297, label %if.else386]
if.then297: ; preds = %if.else
indirectbr i8* undef, [label %PREMATURE, label %if.end307]
if.end307: ; preds = %if.then297
indirectbr i8* undef, [label %if.end314, label %FAIL]
if.end314: ; preds = %if.end307
indirectbr i8* undef, [label %if.end340]
if.end340: ; preds = %while.end334
indirectbr i8* undef, [label %PREMATURE, label %if.end348]
if.end348: ; preds = %if.end340
%incdec.ptr356 = getelementptr inbounds i8* undef, i64 2
indirectbr i8* undef, [label %while.cond179]
if.else386: ; preds = %if.else
indirectbr i8* undef, [label %while.end453, label %if.end434]
if.end434: ; preds = %if.then428, %if.end421
indirectbr i8* undef, [label %while.cond179]
while.end453: ; preds = %if.else386, %land.rhs184, %while.cond179
indirectbr i8* undef, [label %PREMATURE, label %if.end459]
if.end459: ; preds = %while.end453
indirectbr i8* undef, [label %if.then465, label %FAIL]
if.then465: ; preds = %if.end459
indirectbr i8* undef, [label %return, label %if.then479]
if.then479: ; preds = %if.then465
indirectbr i8* undef, [label %return]
FAIL: ; preds = %if.end459, %if.end307, %land.lhs.true142, %land.lhs.true131, %while.end
indirectbr i8* undef, [label %DECL_FAIL]
PREMATURE: ; preds = %while.end453, %while.end415, %if.end340, %while.end334, %if.then297, %while.end256, %while.end215
indirectbr i8* undef, [label %return, label %if.then495]
if.then495: ; preds = %PREMATURE
indirectbr i8* undef, [label %return]
DECL_FAIL: ; preds = %if.then488, %FAIL, %land.lhs.true99, %lor.lhs.false, %if.end83, %if.then39, %if.end
indirectbr i8* undef, [label %return]
return: ; preds = %if.then512, %if.end504, %DECL_FAIL, %if.then495, %PREMATURE, %if.then479, %if.then465, %if.then69, %if.end52, %if.end19, %if.then
ret void
}