Fix PR2898. Spiller delete a store for reuse before it knows for sure the reuse happened.

Patch by Lang Hames!

llvm-svn: 57720
This commit is contained in:
Evan Cheng 2008-10-17 20:56:41 +00:00
parent a196618ad0
commit 94169f1021
2 changed files with 155 additions and 11 deletions

View File

@ -1342,6 +1342,7 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
}
// Process all of the spilled uses and all non spilled reg references.
SmallVector<int, 2> PotentialDeadStoreSlots;
for (unsigned j = 0, e = VirtUseOps.size(); j != e; ++j) {
unsigned i = VirtUseOps[j];
MachineOperand &MO = MI.getOperand(i);
@ -1446,17 +1447,14 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
if (MI.getOperand(i).isKill() &&
ReuseSlot <= VirtRegMap::MAX_STACK_SLOT) {
// This was the last use and the spilled value is still available
// for reuse. That means the spill was unnecessary!
MachineInstr* DeadStore = MaybeDeadStores[ReuseSlot];
if (DeadStore) {
DOUT << "Removed dead store:\t" << *DeadStore;
InvalidateKills(*DeadStore, RegKills, KillOps);
VRM.RemoveMachineInstrFromMaps(DeadStore);
MBB.erase(DeadStore);
MaybeDeadStores[ReuseSlot] = NULL;
++NumDSE;
}
// The store of this spilled value is potentially dead, but we
// won't know for certain until we've confirmed that the re-use
// above is valid, which means waiting until the other operands
// are processed. For now we just track the spill slot, we'll
// remove it after the other operands are processed if valid.
PotentialDeadStoreSlots.push_back(ReuseSlot);
}
continue;
} // CanReuse
@ -1560,6 +1558,23 @@ void LocalSpiller::RewriteMBB(MachineBasicBlock &MBB, VirtRegMap &VRM) {
DOUT << '\t' << *prior(MII);
}
// Ok - now we can remove stores that have been confirmed dead.
for (unsigned j = 0, e = PotentialDeadStoreSlots.size(); j != e; ++j) {
// This was the last use and the spilled value is still available
// for reuse. That means the spill was unnecessary!
int PDSSlot = PotentialDeadStoreSlots[j];
MachineInstr* DeadStore = MaybeDeadStores[PDSSlot];
if (DeadStore) {
DOUT << "Removed dead store:\t" << *DeadStore;
InvalidateKills(*DeadStore, RegKills, KillOps);
VRM.RemoveMachineInstrFromMaps(DeadStore);
MBB.erase(DeadStore);
MaybeDeadStores[PDSSlot] = NULL;
++NumDSE;
}
}
DOUT << '\t' << MI;

View File

@ -0,0 +1,129 @@
; RUN: llvm-as < %s | llc -mtriple=x86_64-pc-linux-gnu -regalloc=pbqp -stats |& grep {Number of dead stores elided} | grep 2
; PR2898
%struct.BiContextType = type { i16, i8 }
%struct.Bitstream = type { i32, i32, i32, i32, i8*, i32 }
%struct.DataPartition = type { %struct.Bitstream*, %struct.DecodingEnvironment, i32 (%struct.SyntaxElement*, %struct.ImageParameters*, %struct.DataPartition*)* }
%struct.DecRefPicMarking_t = type { i32, i32, i32, i32, i32, %struct.DecRefPicMarking_t* }
%struct.DecodingEnvironment = type { i32, i32, i32, i32, i32, i8*, i32* }
%struct.ImageParameters = type { i32, i32, i32, i32, i32*, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, [16 x [16 x i16]], [6 x [32 x i32]], [16 x [16 x i32]], [4 x [12 x [4 x [4 x i32]]]], [16 x i32], i8**, i32*, i32***, i32**, i32, i32, i32, i32, %struct.Slice*, %struct.Macroblock*, i32, i32, i32, i32, i32, i32, %struct.DecRefPicMarking_t*, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, [3 x i32], i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32***, i32***, i32****, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, [3 x [2 x i32]], [3 x [2 x i32]], i32, i32, i64, i64, %struct.timeb, %struct.timeb, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 }
%struct.Macroblock = type { i32, [2 x i32], i32, i32, %struct.Macroblock*, %struct.Macroblock*, i32, [2 x [4 x [4 x [2 x i32]]]], i32, i64, i64, i32, i32, [4 x i8], [4 x i8], i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32, i32 }
%struct.MotionInfoContexts = type { [4 x [11 x %struct.BiContextType]], [2 x [9 x %struct.BiContextType]], [2 x [10 x %struct.BiContextType]], [2 x [6 x %struct.BiContextType]], [4 x %struct.BiContextType], [4 x %struct.BiContextType], [3 x %struct.BiContextType] }
%struct.Slice = type { i32, i32, i32, i32, i32, i32, i32, i32, i32, %struct.DataPartition*, %struct.MotionInfoContexts*, %struct.TextureInfoContexts*, i32, i32*, i32*, i32*, i32, i32*, i32*, i32*, i32 (%struct.ImageParameters*, %struct.inp_par*)*, i32, i32, i32, i32 }
%struct.SyntaxElement = type { i32, i32, i32, i32, i32, i32, i32, i32, void (i32, i32, i32*, i32*)*, void (%struct.SyntaxElement*, %struct.ImageParameters*, %struct.DecodingEnvironment*)* }
%struct.TextureInfoContexts = type { [2 x %struct.BiContextType], [4 x %struct.BiContextType], [3 x [4 x %struct.BiContextType]], [10 x [4 x %struct.BiContextType]], [10 x [15 x %struct.BiContextType]], [10 x [15 x %struct.BiContextType]], [10 x [5 x %struct.BiContextType]], [10 x [5 x %struct.BiContextType]], [10 x [15 x %struct.BiContextType]], [10 x [15 x %struct.BiContextType]] }
%struct.inp_par = type { [1000 x i8], [1000 x i8], [1000 x i8], i32, i32, i32, i32, i32, i32, i32, i32 }
%struct.timeb = type { i64, i16, i16, i16 }
define i1 @itrans8x8_bb15_bb15_2E_ce(%struct.ImageParameters* %img, i32 %ioff, [8 x [8 x i32]]* %m6, i64, i64, i64, i64, i64, i64, i64, i64, i32 %i.2.reg2mem.0, i32* %.out, i32* %.out1, i32* %.out2, i32* %.out3, i32* %.out4, i32* %.out5, i32* %.out6, i32* %.out7, i32* %.out8, i32* %indvar.next58.out) {
newFuncRoot:
br label %bb15.ce
codeRepl1.exitStub: ; preds = %bb15.ce
store i32 %8, i32* %.out
store i32 %24, i32* %.out1
store i32 %25, i32* %.out2
store i32 %26, i32* %.out3
store i32 %27, i32* %.out4
store i32 %53, i32* %.out5
store i32 %55, i32* %.out6
store i32 %57, i32* %.out7
store i32 %59, i32* %.out8
store i32 %indvar.next58, i32* %indvar.next58.out
ret i1 true
bb15.bb15_crit_edge.exitStub: ; preds = %bb15.ce
store i32 %8, i32* %.out
store i32 %24, i32* %.out1
store i32 %25, i32* %.out2
store i32 %26, i32* %.out3
store i32 %27, i32* %.out4
store i32 %53, i32* %.out5
store i32 %55, i32* %.out6
store i32 %57, i32* %.out7
store i32 %59, i32* %.out8
store i32 %indvar.next58, i32* %indvar.next58.out
ret i1 false
bb15.ce: ; preds = %newFuncRoot
%8 = add i32 %i.2.reg2mem.0, %ioff ; <i32> [#uses=3]
%9 = sext i32 %i.2.reg2mem.0 to i64 ; <i64> [#uses=8]
%10 = getelementptr [8 x [8 x i32]]* %m6, i64 0, i64 %9, i64 0 ; <i32*> [#uses=1]
%11 = load i32* %10, align 4 ; <i32> [#uses=2]
%12 = getelementptr [8 x [8 x i32]]* %m6, i64 0, i64 %9, i64 4 ; <i32*> [#uses=1]
%13 = load i32* %12, align 4 ; <i32> [#uses=2]
%14 = add i32 %13, %11 ; <i32> [#uses=2]
%15 = sub i32 %11, %13 ; <i32> [#uses=2]
%16 = getelementptr [8 x [8 x i32]]* %m6, i64 0, i64 %9, i64 2 ; <i32*> [#uses=1]
%17 = load i32* %16, align 4 ; <i32> [#uses=2]
%18 = ashr i32 %17, 1 ; <i32> [#uses=1]
%19 = getelementptr [8 x [8 x i32]]* %m6, i64 0, i64 %9, i64 6 ; <i32*> [#uses=1]
%20 = load i32* %19, align 4 ; <i32> [#uses=2]
%21 = sub i32 %18, %20 ; <i32> [#uses=2]
%22 = ashr i32 %20, 1 ; <i32> [#uses=1]
%23 = add i32 %22, %17 ; <i32> [#uses=2]
%24 = add i32 %23, %14 ; <i32> [#uses=4]
%25 = add i32 %21, %15 ; <i32> [#uses=4]
%26 = sub i32 %15, %21 ; <i32> [#uses=4]
%27 = sub i32 %14, %23 ; <i32> [#uses=4]
%28 = getelementptr [8 x [8 x i32]]* %m6, i64 0, i64 %9, i64 5 ; <i32*> [#uses=1]
%29 = load i32* %28, align 4 ; <i32> [#uses=4]
%30 = getelementptr [8 x [8 x i32]]* %m6, i64 0, i64 %9, i64 3 ; <i32*> [#uses=1]
%31 = load i32* %30, align 4 ; <i32> [#uses=4]
%32 = getelementptr [8 x [8 x i32]]* %m6, i64 0, i64 %9, i64 7 ; <i32*> [#uses=1]
%33 = load i32* %32, align 4 ; <i32> [#uses=4]
%34 = ashr i32 %33, 1 ; <i32> [#uses=1]
%35 = sub i32 %29, %31 ; <i32> [#uses=1]
%36 = sub i32 %35, %33 ; <i32> [#uses=1]
%37 = sub i32 %36, %34 ; <i32> [#uses=2]
%38 = getelementptr [8 x [8 x i32]]* %m6, i64 0, i64 %9, i64 1 ; <i32*> [#uses=1]
%39 = load i32* %38, align 4 ; <i32> [#uses=4]
%40 = ashr i32 %31, 1 ; <i32> [#uses=1]
%41 = add i32 %33, %39 ; <i32> [#uses=1]
%42 = sub i32 %41, %31 ; <i32> [#uses=1]
%43 = sub i32 %42, %40 ; <i32> [#uses=2]
%44 = ashr i32 %29, 1 ; <i32> [#uses=1]
%45 = sub i32 %33, %39 ; <i32> [#uses=1]
%46 = add i32 %45, %29 ; <i32> [#uses=1]
%47 = add i32 %46, %44 ; <i32> [#uses=2]
%48 = ashr i32 %39, 1 ; <i32> [#uses=1]
%49 = add i32 %29, %31 ; <i32> [#uses=1]
%50 = add i32 %49, %39 ; <i32> [#uses=1]
%51 = add i32 %50, %48 ; <i32> [#uses=2]
%52 = ashr i32 %51, 2 ; <i32> [#uses=1]
%53 = add i32 %52, %37 ; <i32> [#uses=4]
%54 = ashr i32 %37, 2 ; <i32> [#uses=1]
%55 = sub i32 %51, %54 ; <i32> [#uses=4]
%56 = ashr i32 %47, 2 ; <i32> [#uses=1]
%57 = add i32 %56, %43 ; <i32> [#uses=4]
%58 = ashr i32 %43, 2 ; <i32> [#uses=1]
%59 = sub i32 %58, %47 ; <i32> [#uses=4]
%60 = add i32 %55, %24 ; <i32> [#uses=1]
%61 = sext i32 %8 to i64 ; <i64> [#uses=8]
%62 = getelementptr %struct.ImageParameters* %img, i64 0, i32 27, i64 %0, i64 %61 ; <i32*> [#uses=1]
store i32 %60, i32* %62, align 4
%63 = add i32 %59, %25 ; <i32> [#uses=1]
%64 = getelementptr %struct.ImageParameters* %img, i64 0, i32 27, i64 %1, i64 %61 ; <i32*> [#uses=1]
store i32 %63, i32* %64, align 4
%65 = add i32 %57, %26 ; <i32> [#uses=1]
%66 = getelementptr %struct.ImageParameters* %img, i64 0, i32 27, i64 %2, i64 %61 ; <i32*> [#uses=1]
store i32 %65, i32* %66, align 4
%67 = add i32 %53, %27 ; <i32> [#uses=1]
%68 = getelementptr %struct.ImageParameters* %img, i64 0, i32 27, i64 %3, i64 %61 ; <i32*> [#uses=1]
store i32 %67, i32* %68, align 4
%69 = sub i32 %27, %53 ; <i32> [#uses=1]
%70 = getelementptr %struct.ImageParameters* %img, i64 0, i32 27, i64 %4, i64 %61 ; <i32*> [#uses=1]
store i32 %69, i32* %70, align 4
%71 = sub i32 %26, %57 ; <i32> [#uses=1]
%72 = getelementptr %struct.ImageParameters* %img, i64 0, i32 27, i64 %5, i64 %61 ; <i32*> [#uses=1]
store i32 %71, i32* %72, align 4
%73 = sub i32 %25, %59 ; <i32> [#uses=1]
%74 = getelementptr %struct.ImageParameters* %img, i64 0, i32 27, i64 %6, i64 %61 ; <i32*> [#uses=1]
store i32 %73, i32* %74, align 4
%75 = sub i32 %24, %55 ; <i32> [#uses=1]
%76 = getelementptr %struct.ImageParameters* %img, i64 0, i32 27, i64 %7, i64 %61 ; <i32*> [#uses=1]
store i32 %75, i32* %76, align 4
%indvar.next58 = add i32 %i.2.reg2mem.0, 1 ; <i32> [#uses=3]
%exitcond59 = icmp eq i32 %indvar.next58, 8 ; <i1> [#uses=1]
br i1 %exitcond59, label %codeRepl1.exitStub, label %bb15.bb15_crit_edge.exitStub
}