Commit 5babbb14 authored by Travis Hance's avatar Travis Hance

Merge pull request #670 from undingen/rewriter_alloc

rewriter: use lea to allocate stack space
parents bbc95869 08266dc3
......@@ -145,6 +145,15 @@ void Assembler::emitSIB(uint8_t scalebits, uint8_t index, uint8_t base) {
emitByte((scalebits << 6) | (index << 3) | base);
}
int Assembler::getModeFromOffset(int offset) const {
if (offset == 0)
return 0b00;
else if (-0x80 <= offset && offset < 0x80)
return 0b01;
else
return 0b10;
}
void Assembler::mov(Immediate val, Register dest, bool force_64bit_load) {
force_64bit_load = force_64bit_load || !val.fitsInto32Bit();
......@@ -178,15 +187,7 @@ void Assembler::movq(Immediate src, Indirect dest) {
emitByte(0xc7);
bool needssib = (dest_idx == 0b100);
int mode;
if (dest.offset == 0)
mode = 0b00;
else if (-0x80 <= dest.offset && dest.offset < 0x80)
mode = 0b01;
else
mode = 0b10;
int mode = getModeFromOffset(dest.offset);
emitModRM(mode, 0, dest_idx);
if (needssib)
......@@ -246,15 +247,7 @@ void Assembler::mov(Register src, Indirect dest) {
emitByte(0x89);
bool needssib = (dest_idx == 0b100);
int mode;
if (dest.offset == 0)
mode = 0b00;
else if (-0x80 <= dest.offset && dest.offset < 0x80)
mode = 0b01;
else
mode = 0b10;
int mode = getModeFromOffset(dest.offset);
emitModRM(mode, src_idx, dest_idx);
if (needssib)
......@@ -450,15 +443,7 @@ void Assembler::movsd(XMMRegister src, Indirect dest) {
emitByte(0x11);
bool needssib = (dest_idx == 0b100);
int mode;
if (dest.offset == 0)
mode = 0b00;
else if (-0x80 <= dest.offset && dest.offset < 0x80)
mode = 0b01;
else
mode = 0b10;
int mode = getModeFromOffset(dest.offset);
emitModRM(mode, src_idx, dest_idx);
if (needssib)
......@@ -809,8 +794,6 @@ void Assembler::cmp(Indirect mem, Register reg) {
}
void Assembler::lea(Indirect mem, Register reg) {
RELEASE_ASSERT(mem.base != RSP && mem.base != R12, "We have to generate the SIB byte...");
int mem_idx = mem.base.regnum;
int reg_idx = reg.regnum;
......@@ -830,14 +813,17 @@ void Assembler::lea(Indirect mem, Register reg) {
emitRex(rex);
emitByte(0x8D);
if (mem.offset == 0) {
emitModRM(0b00, reg_idx, mem_idx);
} else if (-0x80 <= mem.offset && mem.offset < 0x80) {
emitModRM(0b01, reg_idx, mem_idx);
bool needssib = (mem_idx == 0b100);
int mode = getModeFromOffset(mem.offset);
emitModRM(mode, reg_idx, mem_idx);
if (needssib)
emitSIB(0b00, 0b100, mem_idx);
if (mode == 0b01) {
emitByte(mem.offset);
} else {
} else if (mode == 0b10) {
assert((-1L << 31) <= mem.offset && mem.offset < (1L << 31) - 1);
emitModRM(0b10, reg_idx, mem_idx);
emitInt(mem.offset, 4);
}
}
......
......@@ -88,6 +88,8 @@ private:
void emitSIB(uint8_t scalebits, uint8_t index, uint8_t base);
void emitArith(Immediate imm, Register reg, int opcode);
int getModeFromOffset(int offset) const;
public:
Assembler(uint8_t* start, int size) : start_addr(start), end_addr(start + size), addr(start_addr), failed(false) {}
......
......@@ -1358,11 +1358,9 @@ int Rewriter::_allocate(RewriterVar* result, int n) {
assembler::Register r = result->initializeInReg();
// TODO should be a LEA instruction
// In fact, we could do something like we do for constants and only load
// TODO we could do something like we do for constants and only load
// this when necessary, so it won't spill. Is that worth?
assembler->mov(assembler::RSP, r);
assembler->add(assembler::Immediate(8 * a + rewrite->getScratchRspOffset()), r);
assembler->lea(assembler::Indirect(assembler::RSP, 8 * a + rewrite->getScratchRspOffset()), r);
assertConsistent();
result->releaseIfNoUses();
......
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