Some stackslots are allocated to vregs which have no real reference.

LiveRangeEdit::eliminateDeadDef is used to remove dead define instructions
after rematerialization. To remove a VNI for a vreg from its LiveInterval,
LiveIntervals::removeVRegDefAt is used. However, after non-PHI VNIs are all
removed, PHI VNI are still left in the LiveInterval. Such unused vregs will
be kept in RegsToSpill[] at the end of InlineSpiller::reMaterializeAll and
spiller will allocate stackslot for them.

The fix is to get rid of unused reg by checking whether it has non-dbg
reference instead of whether it has non-empty interval.

llvm-svn: 259895
This commit is contained in:
Wei Mi 2016-02-05 18:14:24 +00:00
parent 6e1967ef66
commit a62f058989
2 changed files with 255 additions and 7 deletions
llvm
lib/CodeGen
test/CodeGen/X86

View File

@ -981,18 +981,20 @@ void InlineSpiller::reMaterializeAll() {
DEBUG(dbgs() << "Remat created " << DeadDefs.size() << " dead defs.\n");
Edit->eliminateDeadDefs(DeadDefs, RegsToSpill);
// Get rid of deleted and empty intervals.
// LiveRangeEdit::eliminateDeadDef is used to remove dead define instructions
// after rematerialization. To remove a VNI for a vreg from its LiveInterval,
// LiveIntervals::removeVRegDefAt is used. However, after non-PHI VNIs are all
// removed, PHI VNI are still left in the LiveInterval.
// So to get rid of unused reg, we need to check whether it has non-dbg
// reference instead of whether it has non-empty interval.
unsigned ResultPos = 0;
for (unsigned Reg : RegsToSpill) {
if (!LIS.hasInterval(Reg))
continue;
LiveInterval &LI = LIS.getInterval(Reg);
if (LI.empty()) {
if (MRI.reg_nodbg_empty(Reg)) {
Edit->eraseVirtReg(Reg);
continue;
}
assert((LIS.hasInterval(Reg) && !LIS.getInterval(Reg).empty()) &&
"Reg with empty interval has reference");
RegsToSpill[ResultPos++] = Reg;
}
RegsToSpill.erase(RegsToSpill.begin() + ResultPos, RegsToSpill.end());

View File

@ -0,0 +1,246 @@
; PR26374: Check no stack slots are allocated for vregs which have no real reference.
; RUN: llc < %s | FileCheck %s
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
%struct.ImageParameters = type { i32, i32, [0 x [16 x i16]] }
%struct.InputParameters = type { i32, i32 }
@c = common global %struct.ImageParameters* null, align 8
@a = common global i16** null, align 8
@d = common global [6 x i32] zeroinitializer, align 16
@b = common global %struct.InputParameters* null, align 8
@e = common global [4 x i32] zeroinitializer, align 16
; It is not easy to check there is no unused holes in stack allocated for spills,
; so simply check the size of stack allocated cannot exceed 350.
; (408 is used before the fix for PR26374. 344 is used after the fix).
;
; CHECK-LABEL: @fn
; CHECK: subq {{\$3[0-4][0-9]}}, %rsp
; Function Attrs: nounwind uwtable
define i32 @fn() #0 {
entry:
%n = alloca [8 x [8 x i32]], align 16
%tmp = bitcast [8 x [8 x i32]]* %n to i8*
call void @llvm.lifetime.start(i64 256, i8* %tmp) #3
%tmp1 = bitcast [8 x [8 x i32]]* %n to i8*
%arraydecay.1 = getelementptr inbounds [8 x [8 x i32]], [8 x [8 x i32]]* %n, i64 0, i64 1, i64 0
%tmp2 = bitcast i32* %arraydecay.1 to i8*
%arraydecay.2 = getelementptr inbounds [8 x [8 x i32]], [8 x [8 x i32]]* %n, i64 0, i64 2, i64 0
%tmp3 = bitcast i32* %arraydecay.2 to i8*
%arraydecay.3 = getelementptr inbounds [8 x [8 x i32]], [8 x [8 x i32]]* %n, i64 0, i64 3, i64 0
%tmp4 = bitcast i32* %arraydecay.3 to i8*
%arraydecay.4 = getelementptr inbounds [8 x [8 x i32]], [8 x [8 x i32]]* %n, i64 0, i64 4, i64 0
%tmp5 = bitcast i32* %arraydecay.4 to i8*
%arraydecay.5 = getelementptr inbounds [8 x [8 x i32]], [8 x [8 x i32]]* %n, i64 0, i64 5, i64 0
%tmp6 = bitcast i32* %arraydecay.5 to i8*
%arraydecay.6 = getelementptr inbounds [8 x [8 x i32]], [8 x [8 x i32]]* %n, i64 0, i64 6, i64 0
%tmp7 = bitcast i32* %arraydecay.6 to i8*
%arraydecay.7 = getelementptr inbounds [8 x [8 x i32]], [8 x [8 x i32]]* %n, i64 0, i64 7, i64 0
%tmp8 = bitcast i32* %arraydecay.7 to i8*
br label %for.body
for.body: ; preds = %for.inc73, %entry
%q.0131 = phi i32 [ 0, %entry ], [ %inc74, %for.inc73 ]
%m.0130 = phi i32 [ 0, %entry ], [ %m.4, %for.inc73 ]
%div = sdiv i32 %q.0131, 2
%shl = shl i32 %div, 3
%rem = srem i32 %q.0131, 2
%shl1 = shl nsw i32 %rem, 3
%tmp9 = sext i32 %shl1 to i64
%tmp10 = sext i32 %shl to i64
%tmp11 = or i32 %shl1, 4
%tmp12 = sext i32 %tmp11 to i64
%tmp13 = or i32 %shl, 4
%tmp14 = sext i32 %tmp13 to i64
br label %for.body4
for.body4: ; preds = %for.inc48, %for.body
%indvars.iv148 = phi i64 [ %tmp10, %for.body ], [ %indvars.iv.next149, %for.inc48 ]
%m.1126 = phi i32 [ %m.0130, %for.body ], [ %m.3.lcssa, %for.inc48 ]
%tmp15 = load %struct.ImageParameters*, %struct.ImageParameters** @c, align 8
%opix_y = getelementptr inbounds %struct.ImageParameters, %struct.ImageParameters* %tmp15, i64 0, i32 1
%tmp16 = load i32, i32* %opix_y, align 4
%tmp17 = trunc i64 %indvars.iv148 to i32
%add5 = add nsw i32 %tmp16, %tmp17
%tmp18 = sub nuw nsw i64 %indvars.iv148, %tmp10
%tmp19 = sext i32 %add5 to i64
%tmp20 = add nsw i64 %tmp19, 1
%tmp21 = or i64 %indvars.iv148, 1
%tmp22 = or i64 %tmp18, 1
%tmp23 = add nsw i64 %tmp19, 2
%tmp24 = or i64 %indvars.iv148, 2
%tmp25 = or i64 %tmp18, 2
%tmp26 = add nsw i64 %tmp19, 3
%tmp27 = or i64 %indvars.iv148, 3
%tmp28 = or i64 %tmp18, 3
br label %for.body9
for.body9: ; preds = %for.inc45.for.body9_crit_edge, %for.body4
%tmp29 = phi %struct.ImageParameters* [ %tmp15, %for.body4 ], [ %.pre, %for.inc45.for.body9_crit_edge ]
%indvars.iv145 = phi i64 [ %tmp9, %for.body4 ], [ %indvars.iv.next146, %for.inc45.for.body9_crit_edge ]
%m.2124 = phi i32 [ %m.1126, %for.body4 ], [ %m.3, %for.inc45.for.body9_crit_edge ]
%opix_x = getelementptr inbounds %struct.ImageParameters, %struct.ImageParameters* %tmp29, i64 0, i32 0
%tmp30 = load i32, i32* %opix_x, align 4
%tmp31 = trunc i64 %indvars.iv145 to i32
%add10 = add nsw i32 %tmp30, %tmp31
tail call void @LumaPrediction4x4(i32 %tmp31, i32 %tmp17, i32 0, i32 0, i32 0, i16 signext 0, i16 signext 0) #3
%tmp32 = load i16**, i16*** @a, align 8
%tmp33 = load %struct.ImageParameters*, %struct.ImageParameters** @c, align 8
%tmp34 = sub nuw nsw i64 %indvars.iv145, %tmp9
%tmp35 = sext i32 %add10 to i64
br label %for.cond14.preheader
for.cond14.preheader: ; preds = %for.body9
%arrayidx = getelementptr inbounds i16*, i16** %tmp32, i64 %tmp19
%tmp36 = load i16*, i16** %arrayidx, align 8
%arrayidx20 = getelementptr inbounds i16, i16* %tmp36, i64 %tmp35
%arrayidx26 = getelementptr inbounds %struct.ImageParameters, %struct.ImageParameters* %tmp33, i64 0, i32 2, i64 %indvars.iv148, i64 %indvars.iv145
%arrayidx35 = getelementptr inbounds [8 x [8 x i32]], [8 x [8 x i32]]* %n, i64 0, i64 %tmp18, i64 %tmp34
%tmp37 = bitcast i16* %arrayidx20 to <4 x i16>*
%tmp38 = load <4 x i16>, <4 x i16>* %tmp37, align 2
%tmp39 = zext <4 x i16> %tmp38 to <4 x i32>
%tmp40 = bitcast i16* %arrayidx26 to <4 x i16>*
%tmp41 = load <4 x i16>, <4 x i16>* %tmp40, align 2
%tmp42 = zext <4 x i16> %tmp41 to <4 x i32>
%tmp43 = sub nsw <4 x i32> %tmp39, %tmp42
%tmp44 = bitcast i32* %arrayidx35 to <4 x i32>*
store <4 x i32> %tmp43, <4 x i32>* %tmp44, align 16
store <4 x i32> %tmp43, <4 x i32>* bitcast ([6 x i32]* @d to <4 x i32>*), align 16
%arrayidx.1 = getelementptr inbounds i16*, i16** %tmp32, i64 %tmp20
%tmp45 = load i16*, i16** %arrayidx.1, align 8
%arrayidx20.1 = getelementptr inbounds i16, i16* %tmp45, i64 %tmp35
%arrayidx26.1 = getelementptr inbounds %struct.ImageParameters, %struct.ImageParameters* %tmp33, i64 0, i32 2, i64 %tmp21, i64 %indvars.iv145
%arrayidx35.1 = getelementptr inbounds [8 x [8 x i32]], [8 x [8 x i32]]* %n, i64 0, i64 %tmp22, i64 %tmp34
%tmp46 = bitcast i16* %arrayidx20.1 to <4 x i16>*
%tmp47 = load <4 x i16>, <4 x i16>* %tmp46, align 2
%tmp48 = zext <4 x i16> %tmp47 to <4 x i32>
%tmp49 = bitcast i16* %arrayidx26.1 to <4 x i16>*
%tmp50 = load <4 x i16>, <4 x i16>* %tmp49, align 2
%tmp51 = zext <4 x i16> %tmp50 to <4 x i32>
%tmp52 = sub nsw <4 x i32> %tmp48, %tmp51
%tmp53 = bitcast i32* %arrayidx35.1 to <4 x i32>*
store <4 x i32> %tmp52, <4 x i32>* %tmp53, align 16
store <4 x i32> %tmp52, <4 x i32>* bitcast (i32* getelementptr inbounds ([6 x i32], [6 x i32]* @d, i64 0, i64 4) to <4 x i32>*), align 16
%arrayidx.2 = getelementptr inbounds i16*, i16** %tmp32, i64 %tmp23
%tmp54 = load i16*, i16** %arrayidx.2, align 8
%arrayidx20.2 = getelementptr inbounds i16, i16* %tmp54, i64 %tmp35
%arrayidx26.2 = getelementptr inbounds %struct.ImageParameters, %struct.ImageParameters* %tmp33, i64 0, i32 2, i64 %tmp24, i64 %indvars.iv145
%arrayidx35.2 = getelementptr inbounds [8 x [8 x i32]], [8 x [8 x i32]]* %n, i64 0, i64 %tmp25, i64 %tmp34
%tmp55 = bitcast i16* %arrayidx20.2 to <4 x i16>*
%tmp56 = load <4 x i16>, <4 x i16>* %tmp55, align 2
%tmp57 = zext <4 x i16> %tmp56 to <4 x i32>
%tmp58 = bitcast i16* %arrayidx26.2 to <4 x i16>*
%tmp59 = load <4 x i16>, <4 x i16>* %tmp58, align 2
%tmp60 = zext <4 x i16> %tmp59 to <4 x i32>
%tmp61 = sub nsw <4 x i32> %tmp57, %tmp60
%tmp62 = bitcast i32* %arrayidx35.2 to <4 x i32>*
store <4 x i32> %tmp61, <4 x i32>* %tmp62, align 16
store <4 x i32> %tmp61, <4 x i32>* bitcast (i32* getelementptr ([6 x i32], [6 x i32]* @d, i64 1, i64 2) to <4 x i32>*), align 16
%arrayidx.3 = getelementptr inbounds i16*, i16** %tmp32, i64 %tmp26
%tmp63 = load i16*, i16** %arrayidx.3, align 8
%arrayidx20.3 = getelementptr inbounds i16, i16* %tmp63, i64 %tmp35
%arrayidx26.3 = getelementptr inbounds %struct.ImageParameters, %struct.ImageParameters* %tmp33, i64 0, i32 2, i64 %tmp27, i64 %indvars.iv145
%arrayidx35.3 = getelementptr inbounds [8 x [8 x i32]], [8 x [8 x i32]]* %n, i64 0, i64 %tmp28, i64 %tmp34
%tmp64 = bitcast i16* %arrayidx20.3 to <4 x i16>*
%tmp65 = load <4 x i16>, <4 x i16>* %tmp64, align 2
%tmp66 = zext <4 x i16> %tmp65 to <4 x i32>
%tmp67 = bitcast i16* %arrayidx26.3 to <4 x i16>*
%tmp68 = load <4 x i16>, <4 x i16>* %tmp67, align 2
%tmp69 = zext <4 x i16> %tmp68 to <4 x i32>
%tmp70 = sub nsw <4 x i32> %tmp66, %tmp69
%tmp71 = bitcast i32* %arrayidx35.3 to <4 x i32>*
store <4 x i32> %tmp70, <4 x i32>* %tmp71, align 16
store <4 x i32> %tmp70, <4 x i32>* bitcast (i32* getelementptr ([6 x i32], [6 x i32]* @d, i64 2, i64 0) to <4 x i32>*), align 16
%tmp72 = load %struct.InputParameters*, %struct.InputParameters** @b, align 8
%rdopt = getelementptr inbounds %struct.InputParameters, %struct.InputParameters* %tmp72, i64 0, i32 0
%tmp73 = load i32, i32* %rdopt, align 4
%cmp42 = icmp eq i32 %tmp73, 0
br i1 %cmp42, label %land.lhs.true, label %if.then
land.lhs.true: ; preds = %for.cond14.preheader
%Transform8x8Mode = getelementptr inbounds %struct.InputParameters, %struct.InputParameters* %tmp72, i64 0, i32 1
%tmp74 = load i32, i32* %Transform8x8Mode, align 4
%tobool = icmp eq i32 %tmp74, 0
br i1 %tobool, label %if.then, label %for.inc45
if.then: ; preds = %land.lhs.true, %for.cond14.preheader
%call = tail call i32 @distortion4x4(i32* nonnull getelementptr inbounds ([6 x i32], [6 x i32]* @d, i64 0, i64 0)) #3
%add44 = add nsw i32 %call, %m.2124
br label %for.inc45
for.inc45: ; preds = %if.then, %land.lhs.true
%m.3 = phi i32 [ %m.2124, %land.lhs.true ], [ %add44, %if.then ]
%cmp8 = icmp slt i64 %indvars.iv145, %tmp12
br i1 %cmp8, label %for.inc45.for.body9_crit_edge, label %for.inc48
for.inc45.for.body9_crit_edge: ; preds = %for.inc45
%indvars.iv.next146 = add nsw i64 %indvars.iv145, 4
%.pre = load %struct.ImageParameters*, %struct.ImageParameters** @c, align 8
br label %for.body9
for.inc48: ; preds = %for.inc45
%m.3.lcssa = phi i32 [ %m.3, %for.inc45 ]
%indvars.iv.next149 = add nsw i64 %indvars.iv148, 4
%cmp3 = icmp slt i64 %indvars.iv148, %tmp14
br i1 %cmp3, label %for.body4, label %for.end50
for.end50: ; preds = %for.inc48
%m.3.lcssa.lcssa = phi i32 [ %m.3.lcssa, %for.inc48 ]
%tmp75 = load %struct.InputParameters*, %struct.InputParameters** @b, align 8
%rdopt51 = getelementptr inbounds %struct.InputParameters, %struct.InputParameters* %tmp75, i64 0, i32 0
%tmp76 = load i32, i32* %rdopt51, align 4
%cmp52 = icmp eq i32 %tmp76, 0
br i1 %cmp52, label %land.lhs.true54, label %for.inc73
land.lhs.true54: ; preds = %for.end50
%Transform8x8Mode55 = getelementptr inbounds %struct.InputParameters, %struct.InputParameters* %tmp75, i64 0, i32 1
%tmp77 = load i32, i32* %Transform8x8Mode55, align 4
%tobool56 = icmp eq i32 %tmp77, 0
br i1 %tobool56, label %for.inc73, label %for.body61.preheader
for.body61.preheader: ; preds = %land.lhs.true54
call void @llvm.memcpy.p0i8.p0i8.i64(i8* nonnull bitcast (i32* getelementptr ([4 x i32], [4 x i32]* @e, i64 4, i64 0) to i8*), i8* %tmp1, i64 32, i32 16, i1 false)
call void @llvm.memcpy.p0i8.p0i8.i64(i8* nonnull bitcast (i32* getelementptr ([4 x i32], [4 x i32]* @e, i64 6, i64 0) to i8*), i8* %tmp2, i64 32, i32 16, i1 false)
call void @llvm.memcpy.p0i8.p0i8.i64(i8* nonnull bitcast (i32* getelementptr ([4 x i32], [4 x i32]* @e, i64 8, i64 0) to i8*), i8* %tmp3, i64 32, i32 16, i1 false)
call void @llvm.memcpy.p0i8.p0i8.i64(i8* nonnull bitcast (i32* getelementptr ([4 x i32], [4 x i32]* @e, i64 10, i64 0) to i8*), i8* %tmp4, i64 32, i32 16, i1 false)
call void @llvm.memcpy.p0i8.p0i8.i64(i8* nonnull bitcast (i32* getelementptr ([4 x i32], [4 x i32]* @e, i64 12, i64 0) to i8*), i8* %tmp5, i64 32, i32 16, i1 false)
call void @llvm.memcpy.p0i8.p0i8.i64(i8* nonnull bitcast (i32* getelementptr ([4 x i32], [4 x i32]* @e, i64 14, i64 0) to i8*), i8* %tmp6, i64 32, i32 16, i1 false)
call void @llvm.memcpy.p0i8.p0i8.i64(i8* nonnull bitcast (i32* getelementptr ([4 x i32], [4 x i32]* @e, i64 16, i64 0) to i8*), i8* %tmp7, i64 32, i32 16, i1 false)
call void @llvm.memcpy.p0i8.p0i8.i64(i8* nonnull bitcast (i32* getelementptr ([4 x i32], [4 x i32]* @e, i64 18, i64 0) to i8*), i8* %tmp8, i64 32, i32 16, i1 false)
%call70 = tail call i32 @distortion4x4(i32* nonnull getelementptr inbounds ([4 x i32], [4 x i32]* @e, i64 0, i64 0)) #3
%add71 = add nsw i32 %call70, %m.3.lcssa.lcssa
br label %for.inc73
for.inc73: ; preds = %for.body61.preheader, %land.lhs.true54, %for.end50
%m.4 = phi i32 [ %add71, %for.body61.preheader ], [ %m.3.lcssa.lcssa, %land.lhs.true54 ], [ %m.3.lcssa.lcssa, %for.end50 ]
%inc74 = add nuw nsw i32 %q.0131, 1
%exitcond156 = icmp eq i32 %inc74, 4
br i1 %exitcond156, label %for.end75, label %for.body
for.end75: ; preds = %for.inc73
%m.4.lcssa = phi i32 [ %m.4, %for.inc73 ]
call void @llvm.lifetime.end(i64 256, i8* %tmp) #3
ret i32 %m.4.lcssa
}
; Function Attrs: argmemonly nounwind
declare void @llvm.lifetime.start(i64, i8* nocapture) #1
declare void @LumaPrediction4x4(i32, i32, i32, i32, i32, i16 signext, i16 signext) #2
declare i32 @distortion4x4(i32*) #2
; Function Attrs: argmemonly nounwind
declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture readonly, i64, i32, i1) #1
; Function Attrs: argmemonly nounwind
declare void @llvm.lifetime.end(i64, i8* nocapture) #1
attributes #0 = { nounwind uwtable "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #1 = { argmemonly nounwind }
attributes #2 = { "disable-tail-calls"="false" "less-precise-fpmad"="false" "no-frame-pointer-elim"="false" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+fxsr,+mmx,+sse,+sse2" "unsafe-fp-math"="false" "use-soft-float"="false" }
attributes #3 = { nounwind }