Optimizing: Use 16-bit Thumb2 PUSH/POP when possible.
JNI compiler uses the same assembler but always pushes
and pops registers that require the 32-bit PUSH/POP.
Change-Id: I7e857ae799316586cd09d6547cf971ef439af147
diff --git a/compiler/utils/arm/assembler_thumb2.cc b/compiler/utils/arm/assembler_thumb2.cc
index a377cb2..e26e3d2 100644
--- a/compiler/utils/arm/assembler_thumb2.cc
+++ b/compiler/utils/arm/assembler_thumb2.cc
@@ -374,16 +374,11 @@
Register base,
RegList regs,
Condition cond) {
- if (__builtin_popcount(regs) == 1) {
+ CHECK_NE(regs, 0u); // Do not use ldm if there's nothing to load.
+ if (IsPowerOfTwo(regs)) {
// Thumb doesn't support one reg in the list.
// Find the register number.
- int reg = 0;
- while (reg < 16) {
- if ((regs & (1 << reg)) != 0) {
- break;
- }
- ++reg;
- }
+ int reg = CTZ(static_cast<uint32_t>(regs));
CHECK_LT(reg, 16);
CHECK(am == DB_W); // Only writeback is supported.
ldr(static_cast<Register>(reg), Address(base, kRegisterSize, Address::PostIndex), cond);
@@ -397,16 +392,11 @@
Register base,
RegList regs,
Condition cond) {
- if (__builtin_popcount(regs) == 1) {
+ CHECK_NE(regs, 0u); // Do not use stm if there's nothing to store.
+ if (IsPowerOfTwo(regs)) {
// Thumb doesn't support one reg in the list.
// Find the register number.
- int reg = 0;
- while (reg < 16) {
- if ((regs & (1 << reg)) != 0) {
- break;
- }
- ++reg;
- }
+ int reg = CTZ(static_cast<uint32_t>(regs));
CHECK_LT(reg, 16);
CHECK(am == IA || am == IA_W);
Address::Mode strmode = am == IA ? Address::PreIndex : Address::Offset;
@@ -813,6 +803,7 @@
if (thumb_opcode == 255U /* 0b11111111 */) {
LOG(FATAL) << "Invalid thumb2 opcode " << opcode;
+ UNREACHABLE();
}
int32_t encoding = 0;
@@ -842,6 +833,7 @@
uint32_t imm = ModifiedImmediate(so.encodingThumb());
if (imm == kInvalidModifiedImmediate) {
LOG(FATAL) << "Immediate value cannot fit in thumb2 modified immediate";
+ UNREACHABLE();
}
encoding = B31 | B30 | B29 | B28 |
thumb_opcode << 21 |
@@ -979,6 +971,7 @@
if (thumb_opcode == 255U /* 0b11111111 */) {
LOG(FATAL) << "Invalid thumb1 opcode " << opcode;
+ UNREACHABLE();
}
int16_t encoding = dp_opcode << 14 |
@@ -1116,7 +1109,7 @@
break;
default:
LOG(FATAL) << "This opcode is not an ADD or SUB: " << opcode;
- return;
+ UNREACHABLE();
}
int16_t encoding = dp_opcode << 14 |
@@ -1157,6 +1150,7 @@
case RRX: opcode = 3U /* 0b11 */; amount = 0; break;
default:
LOG(FATAL) << "Unsupported thumb2 shift opcode";
+ UNREACHABLE();
}
// 32 bit.
int32_t encoding = B31 | B30 | B29 | B27 | B25 | B22 |
@@ -1174,7 +1168,8 @@
case LSR: opcode = 1U /* 0b01 */; break;
case ASR: opcode = 2U /* 0b10 */; break;
default:
- LOG(FATAL) << "Unsupported thumb2 shift opcode";
+ LOG(FATAL) << "Unsupported thumb2 shift opcode";
+ UNREACHABLE();
}
int16_t encoding = opcode << 11 | amount << 6 | static_cast<int16_t>(rm) << 3 |
static_cast<int16_t>(rd);
@@ -1198,6 +1193,7 @@
case ROR: opcode = 3U /* 0b11 */; break;
default:
LOG(FATAL) << "Unsupported thumb2 shift opcode";
+ UNREACHABLE();
}
// 32 bit.
int32_t encoding = B31 | B30 | B29 | B28 | B27 | B25 |
@@ -1212,7 +1208,8 @@
case LSR: opcode = 3U /* 0b0011 */; break;
case ASR: opcode = 4U /* 0b0100 */; break;
default:
- LOG(FATAL) << "Unsupported thumb2 shift opcode";
+ LOG(FATAL) << "Unsupported thumb2 shift opcode";
+ UNREACHABLE();
}
int16_t encoding = B14 | opcode << 6 | static_cast<int16_t>(rm) << 3 |
static_cast<int16_t>(rd);
@@ -1241,6 +1238,7 @@
} else {
if (x) {
LOG(FATAL) << "Invalid use of BX";
+ UNREACHABLE();
} else {
if (cond_ == AL) {
// Can use the T4 encoding allowing a 24 bit offset.
@@ -1469,6 +1467,15 @@
CheckCondition(cond);
bool must_be_32bit = force_32bit_;
+ if (!must_be_32bit && base == SP && bam == (load ? IA_W : DB_W) &&
+ (regs & 0xff00 & ~(1 << (load ? PC : LR))) == 0) {
+ // Use 16-bit PUSH/POP.
+ int16_t encoding = B15 | B13 | B12 | (load ? B11 : 0) | B10 |
+ ((regs & (1 << (load ? PC : LR))) != 0 ? B8 : 0) | (regs & 0x00ff);
+ Emit16(encoding);
+ return;
+ }
+
if ((regs & 0xff00) != 0) {
must_be_32bit = true;
}
@@ -1495,6 +1502,7 @@
case DA_W:
case IB_W:
LOG(FATAL) << "LDM/STM mode not supported on thumb: " << bam;
+ UNREACHABLE();
}
if (load) {
// Cannot have SP in the list.
@@ -2068,6 +2076,7 @@
CheckCondition(AL);
if (label->IsBound()) {
LOG(FATAL) << "cbz can only be used to branch forwards";
+ UNREACHABLE();
} else {
uint16_t branchid = EmitCompareAndBranch(rn, static_cast<uint16_t>(label->position_), false);
label->LinkTo(branchid);
@@ -2079,6 +2088,7 @@
CheckCondition(AL);
if (label->IsBound()) {
LOG(FATAL) << "cbnz can only be used to branch forwards";
+ UNREACHABLE();
} else {
uint16_t branchid = EmitCompareAndBranch(rn, static_cast<uint16_t>(label->position_), true);
label->LinkTo(branchid);
