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Fix two serious LSR bugs.

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1. LSR runOnLoop is always returning false regardless if any transformation is made.
2. AddUsersIfInteresting can create new instructions that are added to DeadInsts. But there is a later early exit which prevents them from being freed.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@53193 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evan Cheng 2008-07-07 19:51:32 +00:00
parent 85e9212fcd
commit 1ce75dcbbc
2 changed files with 134 additions and 35 deletions
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70
lib/Transforms/Scalar/LoopStrengthReduce.cpp
View File

@ -1737,6 +1737,7 @@ void LoopStrengthReduce::OptimizeIndvars(Loop *L) {
// live ranges for the IV correctly.
CondUse->Offset = SE->getMinusSCEV(CondUse->Offset, *CondStride);
CondUse->isUseOfPostIncrementedValue = true;
Changed = true;
}
bool LoopStrengthReduce::runOnLoop(Loop *L, LPPassManager &LPM) {
@ -1754,49 +1755,48 @@ bool LoopStrengthReduce::runOnLoop(Loop *L, LPPassManager &LPM) {
for (BasicBlock::iterator I = L->getHeader()->begin(); isa<PHINode>(I); ++I)
AddUsersIfInteresting(I, L, Processed);
// If we have nothing to do, return.
if (IVUsesByStride.empty()) return false;
if (!IVUsesByStride.empty()) {
// Optimize induction variables. Some indvar uses can be transformed to use
// strides that will be needed for other purposes. A common example of this
// is the exit test for the loop, which can often be rewritten to use the
// computation of some other indvar to decide when to terminate the loop.
OptimizeIndvars(L);
// Optimize induction variables. Some indvar uses can be transformed to use
// strides that will be needed for other purposes. A common example of this
// is the exit test for the loop, which can often be rewritten to use the
// computation of some other indvar to decide when to terminate the loop.
OptimizeIndvars(L);
// FIXME: We can widen subreg IV's here for RISC targets. e.g. instead of
// doing computation in byte values, promote to 32-bit values if safe.
// FIXME: Attempt to reuse values across multiple IV's. In particular, we
// could have something like "for(i) { foo(i*8); bar(i*16) }", which should
// be codegened as "for (j = 0;; j+=8) { foo(j); bar(j+j); }" on X86/PPC.
// Need to be careful that IV's are all the same type. Only works for
// intptr_t indvars.
// FIXME: We can widen subreg IV's here for RISC targets. e.g. instead of
// doing computation in byte values, promote to 32-bit values if safe.
// FIXME: Attempt to reuse values across multiple IV's. In particular, we
// could have something like "for(i) { foo(i*8); bar(i*16) }", which should be
// codegened as "for (j = 0;; j+=8) { foo(j); bar(j+j); }" on X86/PPC. Need
// to be careful that IV's are all the same type. Only works for intptr_t
// indvars.
// If we only have one stride, we can more aggressively eliminate some things.
bool HasOneStride = IVUsesByStride.size() == 1;
// If we only have one stride, we can more aggressively eliminate some
// things.
bool HasOneStride = IVUsesByStride.size() == 1;
#ifndef NDEBUG
DOUT << "\nLSR on ";
DEBUG(L->dump());
DOUT << "\nLSR on ";
DEBUG(L->dump());
#endif
// IVsByStride keeps IVs for one particular loop.
assert(IVsByStride.empty() && "Stale entries in IVsByStride?");
// IVsByStride keeps IVs for one particular loop.
assert(IVsByStride.empty() && "Stale entries in IVsByStride?");
// Sort the StrideOrder so we process larger strides first.
std::stable_sort(StrideOrder.begin(), StrideOrder.end(), StrideCompare());
// Sort the StrideOrder so we process larger strides first.
std::stable_sort(StrideOrder.begin(), StrideOrder.end(), StrideCompare());
// Note: this processes each stride/type pair individually. All users passed
// into StrengthReduceStridedIVUsers have the same type AND stride. Also,
// note that we iterate over IVUsesByStride indirectly by using StrideOrder.
// This extra layer of indirection makes the ordering of strides deterministic
// - not dependent on map order.
for (unsigned Stride = 0, e = StrideOrder.size(); Stride != e; ++Stride) {
std::map<SCEVHandle, IVUsersOfOneStride>::iterator SI =
IVUsesByStride.find(StrideOrder[Stride]);
assert(SI != IVUsesByStride.end() && "Stride doesn't exist!");
StrengthReduceStridedIVUsers(SI->first, SI->second, L, HasOneStride);
// Note: this processes each stride/type pair individually. All users
// passed into StrengthReduceStridedIVUsers have the same type AND stride.
// Also, note that we iterate over IVUsesByStride indirectly by using
// StrideOrder. This extra layer of indirection makes the ordering of
// strides deterministic - not dependent on map order.
for (unsigned Stride = 0, e = StrideOrder.size(); Stride != e; ++Stride) {
std::map<SCEVHandle, IVUsersOfOneStride>::iterator SI =
IVUsesByStride.find(StrideOrder[Stride]);
assert(SI != IVUsesByStride.end() && "Stride doesn't exist!");
StrengthReduceStridedIVUsers(SI->first, SI->second, L, HasOneStride);
}
}
// We're done analyzing this loop; release all the state we built up for it.
@ -1839,5 +1839,5 @@ bool LoopStrengthReduce::runOnLoop(Loop *L, LPPassManager &LPM) {
DeleteTriviallyDeadInstructions(DeadInsts);
}
return false;
return Changed;
}

99
test/CodeGen/X86/2008-07-07-DanglingDeadInsts.ll Normal file
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@ -0,0 +1,99 @@
; RUN: llvm-as < %s | llc -mtriple=i386-apple-darwin9
%struct.ogg_stream_state = type { i8*, i32, i32, i32, i32*, i64*, i32, i32, i32, i32, [282 x i8], i32, i32, i32, i32, i32, i64, i64 }
%struct.res_state = type { i32, i32, i32, i32, float*, float*, i32, i32 }
%struct.vorbis_comment = type { i8**, i32*, i32, i8* }
declare i32 @strlen(i8*) nounwind readonly
define i32 @res_init(%struct.res_state* %state, i32 %channels, i32 %outfreq, i32 %infreq, i32 %op1, ...) nounwind {
entry:
br i1 false, label %bb95, label %bb
bb: ; preds = %entry
br i1 false, label %bb95, label %bb24
bb24: ; preds = %bb
br i1 false, label %bb40.preheader, label %bb26
bb26: ; preds = %bb24
ret i32 -1
bb40.preheader: ; preds = %bb24
br i1 false, label %bb39, label %bb49.outer
bb39: ; preds = %bb39, %bb40.preheader
shl i32 0, 1 ; <i32>:0 [#uses=0]
br i1 false, label %bb39, label %bb49.outer
bb49.outer: ; preds = %bb39, %bb40.preheader
getelementptr %struct.res_state* %state, i32 0, i32 3 ; <i32*>:1 [#uses=0]
getelementptr %struct.res_state* %state, i32 0, i32 7 ; <i32*>:2 [#uses=0]
%base10.1 = select i1 false, float* null, float* null ; <float*> [#uses=1]
br label %bb74
bb69: ; preds = %bb74
br label %bb71
bb71: ; preds = %bb74, %bb69
store float 0.000000e+00, float* null, align 4
add i32 0, 1 ; <i32>:3 [#uses=1]
%indvar.next137 = add i32 %indvar136, 1 ; <i32> [#uses=1]
br i1 false, label %bb74, label %bb73
bb73: ; preds = %bb71
%.rec = add i32 %base10.2.ph.rec, 1 ; <i32> [#uses=2]
getelementptr float* %base10.1, i32 %.rec ; <float*>:4 [#uses=1]
br label %bb74
bb74: ; preds = %bb73, %bb71, %bb49.outer
%N13.1.ph = phi i32 [ 0, %bb49.outer ], [ 0, %bb73 ], [ %N13.1.ph, %bb71 ] ; <i32> [#uses=1]
%dest12.2.ph = phi float* [ null, %bb49.outer ], [ %4, %bb73 ], [ %dest12.2.ph, %bb71 ] ; <float*> [#uses=1]
%x8.0.ph = phi i32 [ 0, %bb49.outer ], [ %3, %bb73 ], [ %x8.0.ph, %bb71 ] ; <i32> [#uses=1]
%base10.2.ph.rec = phi i32 [ 0, %bb49.outer ], [ %.rec, %bb73 ], [ %base10.2.ph.rec, %bb71 ] ; <i32> [#uses=2]
%indvar136 = phi i32 [ %indvar.next137, %bb71 ], [ 0, %bb73 ], [ 0, %bb49.outer ] ; <i32> [#uses=1]
br i1 false, label %bb71, label %bb69
bb95: ; preds = %bb, %entry
ret i32 -1
}
define i32 @read_resampled(i8* %d, float** %buffer, i32 %samples) nounwind {
entry:
br i1 false, label %bb17.preheader, label %bb30
bb17.preheader: ; preds = %entry
load i32* null, align 4 ; <i32>:0 [#uses=0]
br label %bb16
bb16: ; preds = %bb16, %bb17.preheader
%i1.036 = phi i32 [ 0, %bb17.preheader ], [ %1, %bb16 ] ; <i32> [#uses=1]
add i32 %i1.036, 1 ; <i32>:1 [#uses=2]
icmp ult i32 %1, 0 ; <i1>:2 [#uses=0]
br label %bb16
bb30: ; preds = %entry
ret i32 0
}
define i32 @ogg_stream_reset_serialno(%struct.ogg_stream_state* %os, i32 %serialno) nounwind {
entry:
unreachable
}
define void @vorbis_lsp_to_curve(float* %curve, i32* %map, i32 %n, i32 %ln, float* %lsp, i32 %m, float %amp, float %ampoffset) nounwind {
entry:
unreachable
}
define i32 @vorbis_comment_query_count(%struct.vorbis_comment* %vc, i8* %tag) nounwind {
entry:
%strlen = call i32 @strlen( i8* null ) ; <i32> [#uses=1]
%endptr = getelementptr i8* null, i32 %strlen ; <i8*> [#uses=0]
unreachable
}
define fastcc i32 @push(%struct.res_state* %state, float* %pool, i32* %poolfill, i32* %offset, float* %dest, i32 %dststep, float* %source, i32 %srcstep, i32 %srclen) nounwind {
entry:
unreachable
}