forked from OSchip/llvm-project
Avoid folding loads that are unsafe to move.
LiveRangeEdit::foldAsLoad() can eliminate a register by folding a load into its only use. Only do that when the load is safe to move, and it won't extend any live ranges. This fixes PR13414. llvm-svn: 160575
This commit is contained in:
Jakob Stoklund Olesen
parent
8c9496a03c
commit
e2cfd0d45a
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@ -177,6 +177,19 @@ bool LiveRangeEdit::foldAsLoad(LiveInterval *LI,
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if (!DefMI || !UseMI)
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return false;
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// Since we're moving the DefMI load, make sure we're not extending any live
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// ranges.
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if (!allUsesAvailableAt(DefMI,
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LIS.getInstructionIndex(DefMI),
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LIS.getInstructionIndex(UseMI)))
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return false;
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// We also need to make sure it is safe to move the load.
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// Assume there are stores between DefMI and UseMI.
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bool SawStore = true;
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if (!DefMI->isSafeToMove(&TII, 0, SawStore))
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return false;
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DEBUG(dbgs() << "Try to fold single def: " << *DefMI
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<< " into single use: " << *UseMI);
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@ -0,0 +1,143 @@
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; RUN: llc < %s -disable-fp-elim -verify-coalescing
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; PR13414
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;
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; During coalescing, remat triggers DCE which deletes the penultimate use of a
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; load. This load should not be folded into the remaining use because it is not
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; safe to move, and it would extend the live range of the address.
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;
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; LiveRangeEdit::foldAsLoad() doesn't extend live ranges, so -verify-coalescing
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; catches the problem.
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target triple = "i386-unknown-linux-gnu"
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%type_a = type { %type_a*, %type_b }
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%type_b = type { %type_c, i32 }
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%type_c = type { i32, %type_d }
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%type_d = type { i64 }
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%type_e = type { %type_c, i64 }
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declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
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define linkonce_odr void @test() nounwind {
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entry:
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br i1 undef, label %while.end.while.end26_crit_edge, label %while.body12.lr.ph
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while.end.while.end26_crit_edge: ; preds = %entry
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br label %while.end26
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while.body12.lr.ph: ; preds = %entry
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br label %while.body12
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while.body12: ; preds = %if.end24, %while.body12.lr.ph
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%tmp = phi %type_a* [ undef, %while.body12.lr.ph ], [ %tmp18, %if.end24 ]
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%ins151154161 = phi i128 [ 0, %while.body12.lr.ph ], [ %phitmp, %if.end24 ]
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%ins135156160 = phi i128 [ 0, %while.body12.lr.ph ], [ %phitmp158, %if.end24 ]
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%ins151 = or i128 0, %ins151154161
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%cmp.i.i.i.i.i67 = icmp sgt i32 undef, 8
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br i1 %cmp.i.i.i.i.i67, label %if.then.i.i.i.i71, label %if.else.i.i.i.i74
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if.then.i.i.i.i71: ; preds = %while.body12
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%call4.i.i.i.i68 = call noalias i8* @malloc(i32 undef) nounwind
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%tmp1 = getelementptr inbounds %type_a* %tmp, i32 0, i32 1, i32 0, i32 1
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%buf_6.i.i.i.i70 = bitcast %type_d* %tmp1 to i8**
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%tmp2 = load i8** %buf_6.i.i.i.i70, align 4
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call void @llvm.memcpy.p0i8.p0i8.i32(i8* undef, i8* %tmp2, i32 undef, i32 1, i1 false) nounwind
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unreachable
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if.else.i.i.i.i74: ; preds = %while.body12
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%i_.i.i.i.i72 = getelementptr inbounds %type_a* %tmp, i32 0, i32 1, i32 0, i32 1, i32 0
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%tmp3 = load i64* %i_.i.i.i.i72, align 4
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%tmp4 = zext i64 %tmp3 to i128
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%tmp5 = shl nuw nsw i128 %tmp4, 32
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%ins148 = or i128 %tmp5, %ins151
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%second3.i.i76 = getelementptr inbounds %type_a* %tmp, i32 0, i32 1, i32 1
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%tmp6 = load i32* %second3.i.i76, align 4
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%tmp7 = zext i32 %tmp6 to i128
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%tmp8 = shl nuw i128 %tmp7, 96
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%mask144 = and i128 %ins148, 79228162495817593519834398720
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%tmp9 = load %type_e** undef, align 4
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%len_.i.i.i.i86 = getelementptr inbounds %type_e* %tmp9, i32 0, i32 0, i32 0
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%tmp10 = load i32* %len_.i.i.i.i86, align 4
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%tmp11 = zext i32 %tmp10 to i128
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%ins135 = or i128 %tmp11, %ins135156160
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%cmp.i.i.i.i.i88 = icmp sgt i32 %tmp10, 8
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br i1 %cmp.i.i.i.i.i88, label %if.then.i.i.i.i92, label %if.else.i.i.i.i95
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if.then.i.i.i.i92: ; preds = %if.else.i.i.i.i74
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%call4.i.i.i.i89 = call noalias i8* @malloc(i32 %tmp10) nounwind
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%ins126 = or i128 0, %ins135
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%tmp12 = getelementptr inbounds %type_e* %tmp9, i32 0, i32 0, i32 1
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%buf_6.i.i.i.i91 = bitcast %type_d* %tmp12 to i8**
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%tmp13 = load i8** %buf_6.i.i.i.i91, align 4
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call void @llvm.memcpy.p0i8.p0i8.i32(i8* %call4.i.i.i.i89, i8* %tmp13, i32 %tmp10, i32 1, i1 false) nounwind
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br label %A
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if.else.i.i.i.i95: ; preds = %if.else.i.i.i.i74
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%i_.i.i.i.i93 = getelementptr inbounds %type_e* %tmp9, i32 0, i32 0, i32 1, i32 0
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br label %A
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A: ; preds = %if.else.i.i.i.i95, %if.then.i.i.i.i92
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%ins135157 = phi i128 [ %ins126, %if.then.i.i.i.i92 ], [ undef, %if.else.i.i.i.i95 ]
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%second3.i.i97 = getelementptr inbounds %type_e* %tmp9, i32 0, i32 1
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%tmp14 = load i64* %second3.i.i97, align 4
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%tmp15 = trunc i64 %tmp14 to i32
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%cmp.i99 = icmp sgt i32 %tmp6, %tmp15
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%tmp16 = trunc i128 %ins135157 to i32
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%cmp.i.i.i.i.i.i101 = icmp sgt i32 %tmp16, 8
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br i1 %cmp.i.i.i.i.i.i101, label %if.then.i.i.i.i.i103, label %B
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if.then.i.i.i.i.i103: ; preds = %A
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unreachable
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B: ; preds = %A
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%tmp17 = trunc i128 %ins148 to i32
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%cmp.i.i.i.i.i.i83 = icmp sgt i32 %tmp17, 8
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br i1 %cmp.i.i.i.i.i.i83, label %if.then.i.i.i.i.i85, label %C
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if.then.i.i.i.i.i85: ; preds = %B
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unreachable
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C: ; preds = %B
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br i1 %cmp.i99, label %if.then17, label %if.end24
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if.then17: ; preds = %C
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br i1 false, label %if.then.i.i.i.i.i43, label %D
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if.then.i.i.i.i.i43: ; preds = %if.then17
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unreachable
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D: ; preds = %if.then17
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br i1 undef, label %if.then.i.i.i.i.i, label %E
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if.then.i.i.i.i.i: ; preds = %D
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unreachable
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E: ; preds = %D
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br label %if.end24
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if.end24: ; preds = %E, %C
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%phitmp = or i128 %tmp8, %mask144
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%phitmp158 = or i128 undef, undef
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%tmp18 = load %type_a** undef, align 4
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%tmp19 = load %type_a** undef, align 4
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%cmp.i49 = icmp eq %type_a* %tmp18, %tmp19
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br i1 %cmp.i49, label %while.cond10.while.end26_crit_edge, label %while.body12
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while.cond10.while.end26_crit_edge: ; preds = %if.end24
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%.pre = load %type_e** undef, align 4
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br label %while.end26
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while.end26: ; preds = %while.cond10.while.end26_crit_edge, %while.end.while.end26_crit_edge
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br i1 undef, label %while.body.lr.ph.i, label %F
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while.body.lr.ph.i: ; preds = %while.end26
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br label %while.body.i
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while.body.i: ; preds = %while.body.i, %while.body.lr.ph.i
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br i1 false, label %while.body.i, label %F
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F: ; preds = %while.body.i, %while.end26
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ret void
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}
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declare noalias i8* @malloc(i32) nounwind
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