[llvm] r198503 - Revert "Fix PR18361: Invalidate LoopDispositions after LoopSimplify hoists things."
Alp Toker
alp at nuanti.com
Sat Jan 4 09:00:45 PST 2014
Author: alp
Date: Sat Jan 4 11:00:45 2014
New Revision: 198503
URL: http://llvm.org/viewvc/llvm-project?rev=198503&view=rev
Log:
Revert "Fix PR18361: Invalidate LoopDispositions after LoopSimplify hoists things."
This commit was the source of crasher PR18384:
While deleting: label %for.cond127
An asserting value handle still pointed to this value!
UNREACHABLE executed at llvm/lib/IR/Value.cpp:671!
Reverting to get the builders green, feel free to re-land after fixing up.
(Renato has a handy isolated repro if you need it.)
This reverts commit r198478.
Removed:
llvm/trunk/test/Transforms/LoopSimplify/ashr-crash.ll
Modified:
llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp
Modified: llvm/trunk/include/llvm/Analysis/ScalarEvolution.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/ScalarEvolution.h?rev=198503&r1=198502&r2=198503&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Analysis/ScalarEvolution.h (original)
+++ llvm/trunk/include/llvm/Analysis/ScalarEvolution.h Sat Jan 4 11:00:45 2014
@@ -784,13 +784,6 @@ namespace llvm {
/// disconnect it from a def-use chain linking it to a loop.
void forgetValue(Value *V);
- /// \brief Called when the client has changed the disposition of values in
- /// this loop.
- ///
- /// We don't have a way to invalidate per-loop dispositions. Clear and
- /// recompute is simpler.
- void forgetLoopDispositions(const Loop *L) { LoopDispositions.clear(); }
-
/// GetMinTrailingZeros - Determine the minimum number of zero bits that S
/// is guaranteed to end in (at every loop iteration). It is, at the same
/// time, the minimum number of times S is divisible by 2. For example,
Modified: llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp?rev=198503&r1=198502&r2=198503&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/LoopSimplify.cpp Sat Jan 4 11:00:45 2014
@@ -309,7 +309,6 @@ ReprocessLoop:
// Attempt to hoist out all instructions except for the
// comparison and the branch.
bool AllInvariant = true;
- bool AnyInvariant = false;
for (BasicBlock::iterator I = ExitingBlock->begin(); &*I != BI; ) {
Instruction *Inst = I++;
// Skip debug info intrinsics.
@@ -317,26 +316,12 @@ ReprocessLoop:
continue;
if (Inst == CI)
continue;
- if (!L->makeLoopInvariant(Inst, AnyInvariant,
- Preheader ? Preheader->getTerminator() : 0)) {
+ if (!L->makeLoopInvariant(Inst, Changed,
+ Preheader ? Preheader->getTerminator() : 0)) {
AllInvariant = false;
break;
}
}
- if (AnyInvariant) {
- Changed = true;
- // If any reachable control flow within this loop has changed, notify
- // ScalarEvolution. Currently assume the parent loop doesn't change
- // (spliting edges doesn't count). If blocks, CFG edges, or other values
- // in the parent loop change, then we need call to forgetLoop() for the
- // parent instead.
- if (SE) {
- SE->forgetLoop(L);
- // The loop disposition of all SCEV expressions that depend on any
- // hoisted values have also changed.
- SE->forgetLoopDispositions(L);
- }
- }
if (!AllInvariant) continue;
// The block has now been cleared of all instructions except for
@@ -349,6 +334,14 @@ ReprocessLoop:
DEBUG(dbgs() << "LoopSimplify: Eliminating exiting block "
<< ExitingBlock->getName() << "\n");
+ // If any reachable control flow within this loop has changed, notify
+ // ScalarEvolution. Currently assume the parent loop doesn't change
+ // (spliting edges doesn't count). If blocks, CFG edges, or other values
+ // in the parent loop change, then we need call to forgetLoop() for the
+ // parent instead.
+ if (SE)
+ SE->forgetLoop(L);
+
assert(pred_begin(ExitingBlock) == pred_end(ExitingBlock));
Changed = true;
LI->removeBlock(ExitingBlock);
Removed: llvm/trunk/test/Transforms/LoopSimplify/ashr-crash.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopSimplify/ashr-crash.ll?rev=198502&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LoopSimplify/ashr-crash.ll (original)
+++ llvm/trunk/test/Transforms/LoopSimplify/ashr-crash.ll (removed)
@@ -1,80 +0,0 @@
-; RUN: opt -basicaa -loop-rotate -licm -instcombine -indvars -loop-unroll -S %s | FileCheck %s
-;
-; PR18361: ScalarEvolution::getAddRecExpr():
-; Assertion `isLoopInvariant(Operands[i],...
-;
-; After a series of loop optimizations, SCEV's LoopDispositions grow stale.
-; In particular, LoopSimplify hoists %cmp4, resulting in this SCEV for %add:
-; {(zext i1 %cmp4 to i32),+,1}<nw><%for.cond1.preheader>
-;
-; When recomputing the SCEV for %ashr, we truncate the operands to get:
-; (zext i1 %cmp4 to i16)
-;
-; This SCEV was never mapped to a value so never invalidated. It's
-; loop disposition is still marked as non-loop-invariant, which is
-; inconsistent with the AddRec.
-
-target datalayout = "e-i64:64-f80:128-n8:16:32:64-S128"
-target triple = "x86_64-apple-macosx"
-
- at d = common global i32 0, align 4
- at a = common global i32 0, align 4
- at c = common global i32 0, align 4
- at b = common global i32 0, align 4
-
-; Check that the def-use chain that leads to the bad SCEV is still
-; there, and part of it is hoisted to the entry block.
-;
-; CHECK-LABEL: @foo
-; CHECK-LABEL: entry:
-; CHECK: %cmp4
-; CHECK-LABEL: for.cond1.preheader:
-; CHECK-LABEL: for.body3:
-; CHECK: %1 = zext i1 %cmp4 to i32
-; CHECK: %xor = xor i32 %1, 1
-define void @foo() {
-entry:
- br label %for.cond
-
-for.cond: ; preds = %for.inc7, %entry
- %storemerge = phi i32 [ 0, %entry ], [ %inc8, %for.inc7 ]
- %f.0 = phi i32 [ undef, %entry ], [ %f.1, %for.inc7 ]
- store i32 %storemerge, i32* @d, align 4
- %cmp = icmp slt i32 %storemerge, 1
- br i1 %cmp, label %for.cond1, label %for.end9
-
-for.cond1: ; preds = %for.cond, %for.body3
- %storemerge1 = phi i32 [ %inc, %for.body3 ], [ 0, %for.cond ]
- %f.1 = phi i32 [ %xor, %for.body3 ], [ %f.0, %for.cond ]
- store i32 %storemerge1, i32* @a, align 4
- %cmp2 = icmp slt i32 %storemerge1, 1
- br i1 %cmp2, label %for.body3, label %for.inc7
-
-for.body3: ; preds = %for.cond1
- %0 = load i32* @c, align 4
- %cmp4 = icmp sge i32 %storemerge1, %0
- %conv = zext i1 %cmp4 to i32
- %1 = load i32* @d, align 4
- %add = add nsw i32 %conv, %1
- %sext = shl i32 %add, 16
- %conv6 = ashr exact i32 %sext, 16
- %xor = xor i32 %conv6, 1
- %inc = add nsw i32 %storemerge1, 1
- br label %for.cond1
-
-for.inc7: ; preds = %for.cond1
- %2 = load i32* @d, align 4
- %inc8 = add nsw i32 %2, 1
- br label %for.cond
-
-for.end9: ; preds = %for.cond
- %cmp10 = icmp sgt i32 %f.0, 0
- br i1 %cmp10, label %if.then, label %if.end
-
-if.then: ; preds = %for.end9
- store i32 0, i32* @b, align 4
- br label %if.end
-
-if.end: ; preds = %if.then, %for.end9
- ret void
-}
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