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Reapply r198478 "Fix PR18361: Invalidate LoopDispositions after LoopSimplify hoists things." 

Now with a fix for PR18384: ValueHandleBase::ValueIsDeleted.

We need to invalidate SCEV's loop info when we delete a block, even if no values are hoisted.

llvm-svn: 198631
This commit is contained in:
Andrew Trick 2014-01-06 19:43:14 +00:00
parent edad1b4797
commit 6796ab424c
4 changed files with 211 additions and 7 deletions
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7
llvm/include/llvm/Analysis/ScalarEvolution.h
View File

@ -784,6 +784,13 @@ 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,

21
llvm/lib/Transforms/Utils/LoopSimplify.cpp
View File

@ -309,6 +309,7 @@ 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.
@ -316,12 +317,19 @@ ReprocessLoop:
continue;
if (Inst == CI)
continue;
if (!L->makeLoopInvariant(Inst, Changed,
Preheader ? Preheader->getTerminator() : 0)) {
if (!L->makeLoopInvariant(Inst, AnyInvariant,
Preheader ? Preheader->getTerminator() : 0)) {
AllInvariant = false;
break;
}
}
if (AnyInvariant) {
Changed = true;
// The loop disposition of all SCEV expressions that depend on any
// hoisted values have also changed.
if (SE)
SE->forgetLoopDispositions(L);
}
if (!AllInvariant) continue;
// The block has now been cleared of all instructions except for
@ -334,11 +342,10 @@ 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.
// Notify ScalarEvolution before deleting this block. 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);

80
llvm/test/Transforms/LoopSimplify/ashr-crash.ll Normal file
View File

@ -0,0 +1,80 @@
; 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"
@d = common global i32 0, align 4
@a = common global i32 0, align 4
@c = common global i32 0, align 4
@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
}

110
llvm/test/Transforms/LoopSimplify/notify-scev.ll Normal file
View File

@ -0,0 +1,110 @@
; RUN: opt -indvars -S %s | FileCheck %s
;
; PR18384: ValueHandleBase::ValueIsDeleted.
;
; Ensure that LoopSimplify calls ScalarEvolution::forgetLoop before
; deleting a block, regardless of whether any values were hoisted out
; of the block.
target datalayout = "e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-darwin"
%struct.Params = type { [2 x [4 x [16 x i16]]] }
; Verify that the loop tail is deleted, and we don't crash!
;
; CHECK-LABEL: @t
; CHECK-LABEL: for.cond127.preheader:
; CHECK-NOT: for.cond127:
; CHECK-LABEL: for.body129:
define void @t() {
entry:
br label %for.body102
for.body102:
br i1 undef, label %for.cond127.preheader, label %for.inc203
for.cond127.preheader:
br label %for.body129
for.cond127:
%cmp128 = icmp slt i32 %inc191, 2
br i1 %cmp128, label %for.body129, label %for.end192
for.body129:
%uv.013 = phi i32 [ 0, %for.cond127.preheader ], [ %inc191, %for.cond127 ]
%idxprom130 = sext i32 %uv.013 to i64
br i1 undef, label %for.cond135.preheader.lr.ph, label %for.end185
for.cond135.preheader.lr.ph:
br i1 undef, label %for.cond135.preheader.lr.ph.split.us, label %for.cond135.preheader.lr.ph.split_crit_edge
for.cond135.preheader.lr.ph.split_crit_edge:
br label %for.cond135.preheader.lr.ph.split
for.cond135.preheader.lr.ph.split.us:
br label %for.cond135.preheader.us
for.cond135.preheader.us:
%block_y.09.us = phi i32 [ 0, %for.cond135.preheader.lr.ph.split.us ], [ %add184.us, %for.cond132.us ]
br i1 true, label %for.cond138.preheader.lr.ph.us, label %for.end178.us
for.end178.us:
%add184.us = add nsw i32 %block_y.09.us, 4
br i1 undef, label %for.end185split.us-lcssa.us, label %for.cond132.us
for.end174.us:
br i1 undef, label %for.cond138.preheader.us, label %for.cond135.for.end178_crit_edge.us
for.inc172.us:
br i1 undef, label %for.cond142.preheader.us, label %for.end174.us
for.body145.us:
%arrayidx163.us = getelementptr inbounds %struct.Params* undef, i64 0, i32 0, i64 %idxprom130, i64 %idxprom146.us
br i1 undef, label %for.body145.us, label %for.inc172.us
for.cond142.preheader.us:
%j.04.us = phi i32 [ %block_y.09.us, %for.cond138.preheader.us ], [ undef, %for.inc172.us ]
%idxprom146.us = sext i32 %j.04.us to i64
br label %for.body145.us
for.cond138.preheader.us:
br label %for.cond142.preheader.us
for.cond132.us:
br i1 undef, label %for.cond135.preheader.us, label %for.cond132.for.end185_crit_edge.us-lcssa.us
for.cond138.preheader.lr.ph.us:
br label %for.cond138.preheader.us
for.cond135.for.end178_crit_edge.us:
br label %for.end178.us
for.end185split.us-lcssa.us:
br label %for.end185split
for.cond132.for.end185_crit_edge.us-lcssa.us:
br label %for.cond132.for.end185_crit_edge
for.cond135.preheader.lr.ph.split:
br label %for.end185split
for.end185split:
br label %for.end185
for.cond132.for.end185_crit_edge:
br label %for.end185
for.end185:
%inc191 = add nsw i32 %uv.013, 1
br i1 false, label %for.end192, label %for.cond127
for.end192:
br label %for.inc203
for.inc203:
br label %for.end205
for.end205:
ret void
}