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Allow a register to be redefined multiple times in a basic block.

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LiveVariableAnalysis was a bit picky about a register only being redefined once,
but that really isn't necessary.

Here is an example of chained INSERT_SUBREGs that we can handle now:

68      %reg1040<def> = INSERT_SUBREG %reg1040, %reg1028<kill>, 14
                register: %reg1040 +[70,134:0)
76      %reg1040<def> = INSERT_SUBREG %reg1040, %reg1029<kill>, 13
                register: %reg1040 replace range with [70,78:1) RESULT: %reg1040,0.000000e+00 = [70,78:1)[78,134:0)  0@78-(134) 1@70-(78)
84      %reg1040<def> = INSERT_SUBREG %reg1040, %reg1030<kill>, 12
                register: %reg1040 replace range with [78,86:2) RESULT: %reg1040,0.000000e+00 = [70,78:1)[78,86:2)[86,134:0)  0@86-(134) 1@70-(78) 2@78-(86)
92      %reg1040<def> = INSERT_SUBREG %reg1040, %reg1031<kill>, 11
                register: %reg1040 replace range with [86,94:3) RESULT: %reg1040,0.000000e+00 = [70,78:1)[78,86:2)[86,94:3)[94,134:0)  0@94-(134) 1@70-(78) 2@78-(86) 3@86-(94)

rdar://problem/8096390

llvm-svn: 106152
This commit is contained in:
Jakob Stoklund Olesen 2010-06-16 21:29:40 +00:00
parent 67b46d6303
commit 4f5d1d7004
2 changed files with 23 additions and 6 deletions
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8
lib/CodeGen/LiveIntervalAnalysis.cpp
View File

@ -434,11 +434,6 @@ void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock *mbb,
// are actually two values in the live interval. Because of this we
// need to take the LiveRegion that defines this register and split it
// into two values.
// Two-address vregs should always only be redefined once. This means
// that at this point, there should be exactly one value number in it.
assert((PartReDef || interval.containsOneValue()) &&
"Unexpected 2-addr liveint!");
SlotIndex DefIndex = interval.getValNumInfo(0)->def.getDefIndex();
SlotIndex RedefIndex = MIIdx.getDefIndex();
if (MO.isEarlyClobber())
RedefIndex = MIIdx.getUseIndex();
@ -446,8 +441,9 @@ void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock *mbb,
const LiveRange *OldLR =
interval.getLiveRangeContaining(RedefIndex.getUseIndex());
VNInfo *OldValNo = OldLR->valno;
SlotIndex DefIndex = OldValNo->def.getDefIndex();
// Delete the initial value, which should be short and continuous,
// Delete the previous value, which should be short and continuous,
// because the 2-addr copy must be in the same MBB as the redef.
interval.removeRange(DefIndex, RedefIndex);

21
test/CodeGen/Thumb2/crash.ll Normal file
View File

@ -0,0 +1,21 @@
; RUN: llc < %s -mtriple=thumbv7-apple-darwin -mcpu=cortex-a8
target datalayout = "e-p:32:32:32-i1:8:32-i8:8:32-i16:16:32-i32:32:32-i64:32:32-f32:32:32-f64:32:32-v64:64:64-v128:128:128-a0:0:32-n32"
target triple = "thumbv7-apple-darwin10"
; This function would crash LiveIntervalAnalysis by creating a chain of 4 INSERT_SUBREGs of the same register.
define arm_apcscc void @NEON_vst4q_u32(i32* nocapture %sp0, i32* nocapture %sp1, i32* nocapture %sp2, i32* nocapture %sp3, i32* %dp) nounwind {
entry:
%0 = bitcast i32* %sp0 to <4 x i32>* ; <<4 x i32>*> [#uses=1]
%1 = load <4 x i32>* %0, align 16 ; <<4 x i32>> [#uses=1]
%2 = bitcast i32* %sp1 to <4 x i32>* ; <<4 x i32>*> [#uses=1]
%3 = load <4 x i32>* %2, align 16 ; <<4 x i32>> [#uses=1]
%4 = bitcast i32* %sp2 to <4 x i32>* ; <<4 x i32>*> [#uses=1]
%5 = load <4 x i32>* %4, align 16 ; <<4 x i32>> [#uses=1]
%6 = bitcast i32* %sp3 to <4 x i32>* ; <<4 x i32>*> [#uses=1]
%7 = load <4 x i32>* %6, align 16 ; <<4 x i32>> [#uses=1]
%8 = bitcast i32* %dp to i8* ; <i8*> [#uses=1]
tail call void @llvm.arm.neon.vst4.v4i32(i8* %8, <4 x i32> %1, <4 x i32> %3, <4 x i32> %5, <4 x i32> %7)
ret void
}
declare void @llvm.arm.neon.vst4.v4i32(i8*, <4 x i32>, <4 x i32>, <4 x i32>, <4 x i32>) nounwind