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[arm] Fix a double-register push operation.

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It is not safe to access memory below sp, and this is also forbidden by
the ABI. When pushing, we must either use an atomic operation (such as
vstm+db_w) or move sp before writing the data.

This patch fixes one stack access, and also adds vpush and vpop helpers
to simplify similar code.

BUG=

Review URL: https://codereview.chromium.org/1378563002

Cr-Commit-Position: refs/heads/master@{#31008}
This commit is contained in:
jacob.bramley 2015-09-29 08:11:18 -07:00 committed by Commit bot
parent 1d03fc17b4
commit f20d646152
4 changed files with 19 additions and 5 deletions
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7
src/arm/assembler-arm.cc
View File

@ -302,6 +302,13 @@ MemOperand::MemOperand(Register rn, int32_t offset, AddrMode am) {
rm_ = no_reg;
offset_ = offset;
am_ = am;
// Accesses below the stack pointer are not safe, and are prohibited by the
// ABI. We can check obvious violations here.
if (rn.is(sp)) {
if (am == Offset) DCHECK_LE(0, offset);
if (am == NegOffset) DCHECK_GE(0, offset);
}
}

8
src/arm/assembler-arm.h
View File

@ -1302,6 +1302,14 @@ class Assembler : public AssemblerBase {
add(sp, sp, Operand(kPointerSize));
}
void vpush(DwVfpRegister src, Condition cond = al) {
vstm(db_w, sp, src, src, cond);
}
void vpop(DwVfpRegister dst, Condition cond = al) {
vldm(ia_w, sp, dst, dst, cond);
}
// Jump unconditionally to given label.
void jmp(Label* L) { b(L, al); }

4
src/arm/lithium-gap-resolver-arm.cc
View File

@ -278,10 +278,10 @@ void LGapResolver::EmitMove(int index) {
MemOperand destination_operand = cgen_->ToMemOperand(destination);
if (in_cycle_) {
// kScratchDoubleReg was used to break the cycle.
__ vstm(db_w, sp, kScratchDoubleReg, kScratchDoubleReg);
__ vpush(kScratchDoubleReg);
__ vldr(kScratchDoubleReg, source_operand);
__ vstr(kScratchDoubleReg, destination_operand);
__ vldm(ia_w, sp, kScratchDoubleReg, kScratchDoubleReg);
__ vpop(kScratchDoubleReg);
} else {
__ vldr(kScratchDoubleReg, source_operand);
__ vstr(kScratchDoubleReg, destination_operand);

5
src/compiler/arm/code-generator-arm.cc
View File

@ -831,10 +831,9 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
}
case kArmPush:
if (instr->InputAt(0)->IsDoubleRegister()) {
__ vstr(i.InputDoubleRegister(0), MemOperand(sp, -kDoubleSize));
__ sub(sp, sp, Operand(kDoubleSize));
__ vpush(i.InputDoubleRegister(0));
} else {
__ Push(i.InputRegister(0));
__ push(i.InputRegister(0));
}
DCHECK_EQ(LeaveCC, i.OutputSBit());
break;