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[IndVars] Fix a bug noticed by inspection

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We were computing the loop exit value, but not ensuring the addrec belonged to the loop whose exit value we were computing.  I couldn't actually trip this; the test case shows the basic setup which *might* trip this, but none of the variations I've tried actually do.

llvm-svn: 369730
This commit is contained in:
Philip Reames 2019-08-23 04:03:23 +00:00
parent 71ceca8ea9
commit 46bf481c61
2 changed files with 63 additions and 1 deletions
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3
lib/Transforms/Scalar/IndVarSimplify.cpp
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@ -644,7 +644,8 @@ bool IndVarSimplify::rewriteLoopExitValues(Loop *L, SCEVExpander &Rewriter) {
if (isa<SCEVCouldNotCompute>(ExitCount))
continue;
if (auto *AddRec = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(Inst)))
ExitValue = AddRec->evaluateAtIteration(ExitCount, *SE);
if (AddRec->getLoop() == L)
ExitValue = AddRec->evaluateAtIteration(ExitCount, *SE);
if (isa<SCEVCouldNotCompute>(ExitValue) ||
!SE->isLoopInvariant(ExitValue, L) ||
!isSafeToExpand(ExitValue, *SE))

61
test/Transforms/IndVarSimplify/rlev-add-me.ll
View File

@ -81,6 +81,67 @@ exit2:
ret i32 %iv.next
}
define i32 @neg_wrong_loop(i32 %n) {
; CHECK-LABEL: @neg_wrong_loop(
; CHECK-NEXT: entry:
; CHECK-NEXT: br label [[WRONG_LOOP:%.*]]
; CHECK: wrong_loop:
; CHECK-NEXT: [[IV2:%.*]] = phi i32 [ 0, [[ENTRY:%.*]] ], [ [[IV2_NEXT:%.*]], [[WRONG_LOOP]] ]
; CHECK-NEXT: [[IV2_NEXT]] = add i32 [[IV2]], 1
; CHECK-NEXT: [[UNKNOWN:%.*]] = load volatile i32, i32* @G
; CHECK-NEXT: [[CMP_UNK:%.*]] = icmp eq i32 [[UNKNOWN]], 0
; CHECK-NEXT: br i1 [[CMP_UNK]], label [[HEADER_PREHEADER:%.*]], label [[WRONG_LOOP]]
; CHECK: header.preheader:
; CHECK-NEXT: [[IV2_LCSSA:%.*]] = phi i32 [ [[IV2]], [[WRONG_LOOP]] ]
; CHECK-NEXT: [[TMP0:%.*]] = add i32 [[N:%.*]], 1
; CHECK-NEXT: br label [[HEADER:%.*]]
; CHECK: header:
; CHECK-NEXT: [[IV:%.*]] = phi i32 [ 0, [[HEADER_PREHEADER]] ], [ [[IV_NEXT:%.*]], [[LATCH:%.*]] ]
; CHECK-NEXT: [[V:%.*]] = load volatile i32, i32* @G
; CHECK-NEXT: [[CMP1:%.*]] = icmp eq i32 [[V]], 0
; CHECK-NEXT: br i1 [[CMP1]], label [[LATCH]], label [[EXIT1:%.*]]
; CHECK: latch:
; CHECK-NEXT: [[IV_NEXT]] = add i32 [[IV]], 1
; CHECK-NEXT: [[EXITCOND:%.*]] = icmp ne i32 [[IV_NEXT]], [[TMP0]]
; CHECK-NEXT: br i1 [[EXITCOND]], label [[HEADER]], label [[EXIT2:%.*]]
; CHECK: exit1:
; CHECK-NEXT: [[IV_LCSSA:%.*]] = phi i32 [ [[IV]], [[HEADER]] ]
; CHECK-NEXT: ret i32 [[IV_LCSSA]]
; CHECK: exit2:
; CHECK-NEXT: [[EXITVAL:%.*]] = phi i32 [ [[IV2_LCSSA]], [[LATCH]] ]
; CHECK-NEXT: ret i32 [[EXITVAL]]
;
entry:
br label %wrong_loop
wrong_loop:
%iv2 = phi i32 [0, %entry], [%iv2.next, %wrong_loop]
%iv2.next = add i32 %iv2, 1
%unknown = load volatile i32, i32* @G
%cmp_unk = icmp eq i32 %unknown, 0
br i1 %cmp_unk, label %header.preheader, label %wrong_loop
header.preheader:
%iv2.lcssa = phi i32 [%iv2, %wrong_loop]
br label %header
header:
%iv = phi i32 [0, %header.preheader], [%iv.next, %latch]
%v = load volatile i32, i32* @G
%cmp1 = icmp eq i32 %v, 0
br i1 %cmp1, label %latch, label %exit1
latch:
%iv.next = add i32 %iv, 1
%cmp2 = icmp ult i32 %iv, %n
br i1 %cmp2, label %header, label %exit2
exit1:
ret i32 %iv
exit2:
%exitval = phi i32 [%iv2.lcssa, %latch]
ret i32 %exitval
}
; TODO: Generalize the code to handle other SCEV expressions
define i32 @test3(i32 %n) {
; CHECK-LABEL: @test3(