Reviewers: ulan, Rodolph Perfetta (ARM),
Message:
Part of the out-of-line constant pool change - PTAL.
Description:
Clean up ARM mov 32bit immediate code in preparation for out of line
constant
pool.
Please review this at https://codereview.chromium.org/138503002/
SVN Base: https://v8.googlecode.com/svn/branches/bleeding_edge
Affected files (+25, -40 lines):
src/arm/assembler-arm.h
src/arm/assembler-arm.cc
M test/cctest/test-disasm-arm.cc
Index: src/arm/assembler-arm.cc
diff --git a/src/arm/assembler-arm.cc b/src/arm/assembler-arm.cc
index
35279e557c8a99d8daccf713b4c3be4e1892d8a9..c82eef20a27b1f911c08874bfd00dd06a898c992
100644
--- a/src/arm/assembler-arm.cc
+++ b/src/arm/assembler-arm.cc
@@ -1054,14 +1054,19 @@ bool Operand::must_output_reloc_info(const
Assembler* assembler) const {
}
-static bool use_movw_movt(const Operand& x, const Assembler* assembler) {
- if (Assembler::use_immediate_embedded_pointer_loads(assembler)) {
+static bool use_mov_immediate_load(const Operand& x,
+ const Assembler* assembler) {
+ if (CpuFeatures::IsSupported(MOVW_MOVT_IMMEDIATE_LOADS) &&
+ (assembler == NULL || !assembler->predictable_code_size())) {
+ // Prefer movw / movt to constant pool if it is more efficient on the
CPU.
return true;
- }
- if (x.must_output_reloc_info(assembler)) {
+ } else if (x.must_output_reloc_info(assembler)) {
+ // Prefer constant pool if data is likely to be patched.
return false;
+ } else {
+ // Otherwise, use immediate load if movw / movt is available.
+ return CpuFeatures::IsSupported(ARMv7);
}
- return CpuFeatures::IsSupported(ARMv7);
}
@@ -1075,7 +1080,7 @@ bool Operand::is_single_instruction(const Assembler*
assembler,
// constant pool is required. For a mov instruction not setting the
// condition code additional instruction conventions can be used.
if ((instr & ~kCondMask) == 13*B21) { // mov, S not set
- return !use_movw_movt(*this, assembler);
+ return !use_mov_immediate_load(*this, assembler);
} else {
// If this is not a mov or mvn instruction there will always an
additional
// instructions - either mov or ldr. The mov might actually be two
@@ -1091,12 +1096,11 @@ bool Operand::is_single_instruction(const
Assembler* assembler,
}
-void Assembler::move_32_bit_immediate(Condition cond,
- Register rd,
- SBit s,
- const Operand& x) {
- if (rd.code() != pc.code() && s == LeaveCC) {
- if (use_movw_movt(x, this)) {
+void Assembler::move_32_bit_immediate(Register rd,
+ const Operand& x,
+ Condition cond) {
+ if (rd.code() != pc.code()) {
+ if (use_mov_immediate_load(x, this)) {
if (x.must_output_reloc_info(this)) {
RecordRelocInfo(x.rmode_, x.imm32_, DONT_USE_CONSTANT_POOL);
// Make sure the movw/movt doesn't get separated.
@@ -1133,20 +1137,9 @@ void Assembler::addrmod1(Instr instr,
CHECK(!rn.is(ip)); // rn should never be ip, or will be trashed
Condition cond = Instruction::ConditionField(instr);
if ((instr & ~kCondMask) == 13*B21) { // mov, S not set
- move_32_bit_immediate(cond, rd, LeaveCC, x);
+ move_32_bit_immediate(rd, x, cond);
} else {
- if ((instr & kMovMvnMask) == kMovMvnPattern) {
- // Moves need to use a constant pool entry.
- RecordRelocInfo(x.rmode_, x.imm32_, USE_CONSTANT_POOL);
- ldr(ip, MemOperand(pc, 0), cond);
- } else if (x.must_output_reloc_info(this)) {
- // Otherwise, use most efficient form of fetching from constant
pool.
- move_32_bit_immediate(cond, ip, LeaveCC, x);
- } else {
- // If this is not a mov or mvn instruction we may still be able
to
- // avoid a constant pool entry by using mvn or movw.
- mov(ip, x, LeaveCC, cond);
- }
+ mov(ip, x, LeaveCC, cond);
addrmod1(instr, rn, rd, Operand(ip));
}
return;
@@ -1814,8 +1807,7 @@ void Assembler::msr(SRegisterFieldMask fields, const
Operand& src,
if (src.must_output_reloc_info(this) ||
!fits_shifter(src.imm32_, &rotate_imm, &immed_8, NULL)) {
// Immediate operand cannot be encoded, load it first to register ip.
- RecordRelocInfo(src.rmode_, src.imm32_);
- ldr(ip, MemOperand(pc, 0), cond);
+ move_32_bit_immediate(ip, src);
msr(fields, Operand(ip), cond);
return;
}
Index: src/arm/assembler-arm.h
diff --git a/src/arm/assembler-arm.h b/src/arm/assembler-arm.h
index
ccb5104206883e9891fce042208538cd8dab2613..c35c80b209e149baaab31278dd11aaeb6ef5c4af
100644
--- a/src/arm/assembler-arm.h
+++ b/src/arm/assembler-arm.h
@@ -1292,12 +1292,6 @@ class Assembler : public AssemblerBase {
// Jump unconditionally to given label.
void jmp(Label* L) { b(L, al); }
- static bool use_immediate_embedded_pointer_loads(
- const Assembler* assembler) {
- return CpuFeatures::IsSupported(MOVW_MOVT_IMMEDIATE_LOADS) &&
- (assembler == NULL || !assembler->predictable_code_size());
- }
-
// Check the code size generated from label to here.
int SizeOfCodeGeneratedSince(Label* label) {
return pc_offset() - label->pos();
@@ -1565,10 +1559,9 @@ class Assembler : public AssemblerBase {
inline void emit(Instr x);
// 32-bit immediate values
- void move_32_bit_immediate(Condition cond,
- Register rd,
- SBit s,
- const Operand& x);
+ void move_32_bit_immediate(Register rd,
+ const Operand& x,
+ Condition cond = al);
// Instruction generation
void addrmod1(Instr instr, Register rn, Register rd, const Operand& x);
Index: test/cctest/test-disasm-arm.cc
diff --git a/test/cctest/test-disasm-arm.cc b/test/cctest/test-disasm-arm.cc
index
cb1b1c798bfbf4249bb3da8e5ffbbcac3ad53b41..56f093eff85cb1a8f6a2926eac147a5cc203dbc8
100644
--- a/test/cctest/test-disasm-arm.cc
+++ b/test/cctest/test-disasm-arm.cc
@@ -272,10 +272,10 @@ TEST(Type0) {
// We only disassemble one instruction so the eor instruction is not
here.
COMPARE(eor(r5, r4, Operand(0x1234), LeaveCC, ne),
"1301c234 movwne ip, #4660");
- // Movw can't do setcc so we don't get that here. Mov immediate with
setcc
- // is pretty strange anyway.
+ // Movw can't do setcc, so first move to ip, then the following
instruction
+ // moves to r5. Mov immediate with setcc is pretty strange anyway.
COMPARE(mov(r5, Operand(0x01234), SetCC, ne),
- "159fc000 ldrne ip, [pc, #+0]");
+ "1301c234 movwne ip, #4660");
// Emit a literal pool now, otherwise this could be dumped later, in
the
// middle of a different test.
EMIT_PENDING_LITERALS();
--
--
v8-dev mailing list
[email protected]
http://groups.google.com/group/v8-dev
---
You received this message because you are subscribed to the Google Groups "v8-dev" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
For more options, visit https://groups.google.com/d/optout.
