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When using ADDri to get the address of a stack object, 255 is a conservative

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limit on the offset that can be materialized without using the register
scavenger.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@106312 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2010-06-18 20:59:25 +00:00
parent 1415a602ad
commit 52c61ec164
2 changed files with 25 additions and 0 deletions
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9
lib/Target/ARM/ARMBaseRegisterInfo.cpp
View File

@ -674,6 +674,15 @@ ARMBaseRegisterInfo::estimateRSStackSizeLimit(MachineFunction &MF) const {
I != E; ++I) {
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
if (!I->getOperand(i).isFI()) continue;
// When using ADDri to get the address of a stack object, 255 is the
// largest offset guaranteed to fit in the immediate offset.
if (I->getOpcode() == ARM::ADDri) {
Limit = std::min(Limit, (1U << 8) - 1);
break;
}
// Otherwise check the addressing mode.
switch (I->getDesc().TSFlags & ARMII::AddrModeMask) {
case ARMII::AddrMode3:
case ARMII::AddrModeT2_i8:

16
test/CodeGen/ARM/crash-O0.ll
View File

@ -10,3 +10,19 @@ entry:
%asmtmp = call %struct0 asm sideeffect "...", "=&r,=&r,r,Ir,r,~{cc},~{memory}"(i32* undef, i32 undef, i32 1) nounwind ; <%0> [#uses=0]
unreachable
}
@.str523 = private constant [256 x i8] c"<Unknown>\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00\00", align 4 ; <[256 x i8]*> [#uses=1]
declare void @llvm.memcpy.p0i8.p0i8.i32(i8* nocapture, i8* nocapture, i32, i32, i1) nounwind
; This function uses the scavenger for an ADDri instruction.
; ARMBaseRegisterInfo::estimateRSStackSizeLimit must return a 255 limit.
define arm_apcscc void @scavence_ADDri() nounwind {
entry:
%letter = alloca i8 ; <i8*> [#uses=0]
%prodvers = alloca [256 x i8] ; <[256 x i8]*> [#uses=1]
%buildver = alloca [256 x i8] ; <[256 x i8]*> [#uses=0]
call void @llvm.memcpy.p0i8.p0i8.i32(i8* undef, i8* getelementptr inbounds ([256 x i8]* @.str523, i32 0, i32 0), i32 256, i32 1, i1 false)
%prodvers2 = bitcast [256 x i8]* %prodvers to i8* ; <i8*> [#uses=1]
call void @llvm.memcpy.p0i8.p0i8.i32(i8* %prodvers2, i8* getelementptr inbounds ([256 x i8]* @.str523, i32 0, i32 0), i32 256, i32 1, i1 false)
unreachable
}