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When computing live intervals for earlyclobber operands, 

we pushed the beginning of the interval back 1, so the
interval would overlap with inputs that die.  We were
also pushing the end of the interval back 1, though,
which means the earlyclobber didn't overlap with other
output operands.  Don't do this.  PR 4964.

llvm-svn: 82342
This commit is contained in:
Dale Johannesen 2009-09-20 00:36:41 +00:00
parent ca2552d9f9
commit a894053a9b
2 changed files with 31 additions and 3 deletions
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19
llvm/lib/CodeGen/LiveIntervalAnalysis.cpp
View File

@ -665,7 +665,8 @@ void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock *mbb,
if (interval.empty()) {
// Get the Idx of the defining instructions.
MachineInstrIndex defIndex = getDefIndex(MIIdx);
// Earlyclobbers move back one.
// Earlyclobbers move back one, so that they overlap the live range
// of inputs.
if (MO.isEarlyClobber())
defIndex = getUseIndex(MIIdx);
VNInfo *ValNo;
@ -690,6 +691,11 @@ void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock *mbb,
MachineInstrIndex killIdx;
if (vi.Kills[0] != mi)
killIdx = getNextSlot(getUseIndex(getInstructionIndex(vi.Kills[0])));
else if (MO.isEarlyClobber())
// Earlyclobbers that die in this instruction move up one extra, to
// compensate for having the starting point moved back one. This
// gets them to overlap the live range of other outputs.
killIdx = getNextSlot(getNextSlot(defIndex));
else
killIdx = getNextSlot(defIndex);
@ -791,7 +797,9 @@ void LiveIntervals::handleVirtualRegisterDef(MachineBasicBlock *mbb,
// range covering the def slot.
if (MO.isDead())
interval.addRange(
LiveRange(RedefIndex, getNextSlot(RedefIndex), OldValNo));
LiveRange(RedefIndex, MO.isEarlyClobber() ?
getNextSlot(getNextSlot(RedefIndex)) :
getNextSlot(RedefIndex), OldValNo));
DEBUG({
errs() << " RESULT: ";
@ -892,9 +900,14 @@ void LiveIntervals::handlePhysicalRegisterDef(MachineBasicBlock *MBB,
// If it is not used after definition, it is considered dead at
// the instruction defining it. Hence its interval is:
// [defSlot(def), defSlot(def)+1)
// For earlyclobbers, the defSlot was pushed back one; the extra
// advance below compensates.
if (MO.isDead()) {
DEBUG(errs() << " dead");
end = getNextSlot(start);
if (MO.isEarlyClobber())
end = getNextSlot(getNextSlot(start));
else
end = getNextSlot(start);
goto exit;
}

15
llvm/test/CodeGen/X86/2009-09-19-earlyclobber.ll Normal file
View File

@ -0,0 +1,15 @@
; RUN: llc < %s | FileCheck %s
; ModuleID = '4964.c'
; PR 4964
; Registers other than RAX, RCX are OK, but they must be different.
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128"
target triple = "x86_64-apple-darwin10.0"
type { i64, i64 } ; type %0
define i64 @flsst(i64 %find) nounwind ssp {
entry:
; CHECK: FOO %rax %rcx
%asmtmp = tail call %0 asm sideeffect "FOO $0 $1 $2", "=r,=&r,rm,~{dirflag},~{fpsr},~{flags},~{cc}"(i64 %find) nounwind ; <%0> [#uses=1]
%asmresult = extractvalue %0 %asmtmp, 0 ; <i64> [#uses=1]
ret i64 %asmresult
}