Don't skip debug instructions when looking for the insertion point of

the cast. If we do, we can end up with

   inst1
   ---------------  < Insertion point
   dbg inst
   new inst

instead of the desired

   inst1
   new inst
   ---------------  < Insertion point
   dbg inst

Another option would be for InsertNoopCastOfTo (or its callers) to move the
insertion point and we would end up with

   inst1
   dbg inst
   new inst
   ---------------  < Insertion point

but that complicates the callers. This fixes PR12018 (and firefox's build).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150884 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Rafael Espindola 2012-02-18 17:22:58 +00:00
parent 31d157ae1a
commit ef4c80e07b
2 changed files with 46 additions and 5 deletions

View File

@ -31,6 +31,12 @@ using namespace llvm;
Value *SCEVExpander::ReuseOrCreateCast(Value *V, Type *Ty,
Instruction::CastOps Op,
BasicBlock::iterator IP) {
// All new or reused instructions must strictly dominate the Builder's
// InsertPt to ensure that the expression's expansion dominates its uses.
// Assert that the requested insertion point works at least for new
// instructions.
assert(SE.DT->dominates(IP, Builder.GetInsertPoint()));
// Check to see if there is already a cast!
for (Value::use_iterator UI = V->use_begin(), E = V->use_end();
UI != E; ++UI) {
@ -38,9 +44,7 @@ Value *SCEVExpander::ReuseOrCreateCast(Value *V, Type *Ty,
if (U->getType() == Ty)
if (CastInst *CI = dyn_cast<CastInst>(U))
if (CI->getOpcode() == Op) {
// If the cast isn't where we want it, fix it. All new or reused
// instructions must strictly dominate the Builder's InsertPt to
// ensure that the expression's expansion dominates its uses.
// If the cast isn't where we want it, fix it.
if (BasicBlock::iterator(CI) != IP
|| IP == Builder.GetInsertPoint()) {
// Create a new cast, and leave the old cast in place in case
@ -124,8 +128,7 @@ Value *SCEVExpander::InsertNoopCastOfTo(Value *V, Type *Ty) {
BasicBlock::iterator IP = I; ++IP;
if (InvokeInst *II = dyn_cast<InvokeInst>(I))
IP = II->getNormalDest()->begin();
while (isa<PHINode>(IP) || isa<DbgInfoIntrinsic>(IP) ||
isa<LandingPadInst>(IP))
while (isa<PHINode>(IP) || isa<LandingPadInst>(IP))
++IP;
return ReuseOrCreateCast(I, Ty, Op, IP);
}

View File

@ -0,0 +1,38 @@
; RUN: opt < %s -loop-reduce
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128-n8:16:32-S128"
%struct.nsTArray = type { i8 }
%struct.nsTArrayHeader = type { i32 }
define void @_Z6foobarR8nsTArray(%struct.nsTArray* %aValues, i32 %foo, %struct.nsTArrayHeader* %bar) nounwind {
entry:
br label %for.body
for.body: ; preds = %_ZN8nsTArray9ElementAtEi.exit, %entry
%i.06 = phi i32 [ %add, %_ZN8nsTArray9ElementAtEi.exit ], [ 0, %entry ]
%call.i = call %struct.nsTArrayHeader* @_ZN8nsTArray4Hdr2Ev() nounwind
%add.ptr.i = getelementptr inbounds %struct.nsTArrayHeader* %call.i, i32 1
%tmp = bitcast %struct.nsTArrayHeader* %add.ptr.i to %struct.nsTArray*
%arrayidx = getelementptr inbounds %struct.nsTArray* %tmp, i32 %i.06
%add = add nsw i32 %i.06, 1
call void @llvm.dbg.value(metadata !{%struct.nsTArray* %aValues}, i64 0, metadata !0) nounwind
br label %_ZN8nsTArray9ElementAtEi.exit
_ZN8nsTArray9ElementAtEi.exit: ; preds = %for.body
%arrayidx.i = getelementptr inbounds %struct.nsTArray* %tmp, i32 %add
call void @_ZN11nsTArray15ComputeDistanceERKS_Rd(%struct.nsTArray* %arrayidx, %struct.nsTArray* %arrayidx.i) nounwind
%cmp = icmp slt i32 %add, %foo
br i1 %cmp, label %for.body, label %for.end
for.end: ; preds = %_ZN8nsTArray9ElementAtEi.exit
ret void
}
declare void @_ZN11nsTArray15ComputeDistanceERKS_Rd(%struct.nsTArray*, %struct.nsTArray*)
declare %struct.nsTArrayHeader* @_ZN8nsTArray4Hdr2Ev()
declare void @llvm.dbg.value(metadata, i64, metadata) nounwind readnone
!0 = metadata !{i32 786689} ; [ DW_TAG_arg_variable ]