Revision: 12887
Author: [email protected]
Date: Wed Nov 7 05:22:03 2012
Log: Simplify some of the startup code for SubStringStub::Generate.
[email protected]
Review URL: https://chromiumcodereview.appspot.com/11098043
Patch from JF Bastien <[email protected]>.
http://code.google.com/p/v8/source/detail?r=12887
Modified:
/branches/bleeding_edge/src/arm/code-stubs-arm.cc
/branches/bleeding_edge/src/arm/macro-assembler-arm.h
/branches/bleeding_edge/src/arm/simulator-arm.cc
=======================================
--- /branches/bleeding_edge/src/arm/code-stubs-arm.cc Thu Oct 18 05:21:42
2012
+++ /branches/bleeding_edge/src/arm/code-stubs-arm.cc Wed Nov 7 05:22:03
2012
@@ -5999,23 +5999,28 @@
STATIC_ASSERT(kSmiTag == 0);
STATIC_ASSERT(kSmiTagSize + kSmiShiftSize == 1);
- // I.e., arithmetic shift right by one un-smi-tags.
- __ mov(r2, Operand(r2, ASR, 1), SetCC);
- __ mov(r3, Operand(r3, ASR, 1), SetCC, cc);
- // If either to or from had the smi tag bit set, then carry is set now.
- __ b(cs, &runtime); // Either "from" or "to" is not a smi.
+ // Arithmetic shift right by one un-smi-tags. In this case we rotate
right
+ // instead because we bail out on non-smi values: ROR and ASR are
equivalent
+ // for smis but they set the flags in a way that's easier to optimize.
+ __ mov(r2, Operand(r2, ROR, 1), SetCC);
+ __ mov(r3, Operand(r3, ROR, 1), SetCC, cc);
+ // If either to or from had the smi tag bit set, then C is set now, and N
+ // has the same value: we rotated by 1, so the bottom bit is now the top
bit.
// We want to bailout to runtime here if From is negative. In that
case, the
// next instruction is not executed and we fall through to bailing out to
- // runtime. pl is the opposite of mi.
- // Both r2 and r3 are untagged integers.
- __ sub(r2, r2, Operand(r3), SetCC, pl);
- __ b(mi, &runtime); // Fail if from > to.
+ // runtime.
+ // Executed if both r2 and r3 are untagged integers.
+ __ sub(r2, r2, Operand(r3), SetCC, cc);
+ // One of the above un-smis or the above SUB could have set N==1.
+ __ b(mi, &runtime); // Either "from" or "to" is not an smi, or from >
to.
// Make sure first argument is a string.
__ ldr(r0, MemOperand(sp, kStringOffset));
STATIC_ASSERT(kSmiTag == 0);
- __ JumpIfSmi(r0, &runtime);
- Condition is_string = masm->IsObjectStringType(r0, r1);
+ // Do a JumpIfSmi, but fold its jump into the subsequent string test.
+ __ tst(r0, Operand(kSmiTagMask));
+ Condition is_string = masm->IsObjectStringType(r0, r1, ne);
+ ASSERT(is_string == eq);
__ b(NegateCondition(is_string), &runtime);
// Short-cut for the case of trivial substring.
=======================================
--- /branches/bleeding_edge/src/arm/macro-assembler-arm.h Fri Oct 19
05:39:59 2012
+++ /branches/bleeding_edge/src/arm/macro-assembler-arm.h Wed Nov 7
05:22:03 2012
@@ -893,12 +893,15 @@
// Load and check the instance type of an object for being a string.
// Loads the type into the second argument register.
- // Returns a condition that will be enabled if the object was a string.
+ // Returns a condition that will be enabled if the object was a string
+ // and the passed-in condition passed. If the passed-in condition failed
+ // then flags remain unchanged.
Condition IsObjectStringType(Register obj,
- Register type) {
- ldr(type, FieldMemOperand(obj, HeapObject::kMapOffset));
- ldrb(type, FieldMemOperand(type, Map::kInstanceTypeOffset));
- tst(type, Operand(kIsNotStringMask));
+ Register type,
+ Condition cond = al) {
+ ldr(type, FieldMemOperand(obj, HeapObject::kMapOffset), cond);
+ ldrb(type, FieldMemOperand(type, Map::kInstanceTypeOffset), cond);
+ tst(type, Operand(kIsNotStringMask), cond);
ASSERT_EQ(0, kStringTag);
return eq;
}
@@ -1202,7 +1205,7 @@
// Souce and destination can be the same register.
void UntagAndJumpIfNotSmi(Register dst, Register src, Label*
non_smi_case);
- // Jump the register contains a smi.
+ // Jump if the register contains a smi.
inline void JumpIfSmi(Register value, Label* smi_label) {
tst(value, Operand(kSmiTagMask));
b(eq, smi_label);
=======================================
--- /branches/bleeding_edge/src/arm/simulator-arm.cc Mon Nov 5 05:28:10
2012
+++ /branches/bleeding_edge/src/arm/simulator-arm.cc Wed Nov 7 05:22:03
2012
@@ -1387,7 +1387,14 @@
}
case ROR: {
- UNIMPLEMENTED();
+ if (shift_amount == 0) {
+ *carry_out = c_flag_;
+ } else {
+ uint32_t left = static_cast<uint32_t>(result) >> shift_amount;
+ uint32_t right = static_cast<uint32_t>(result) << (32 -
shift_amount);
+ result = right | left;
+ *carry_out = (static_cast<uint32_t>(result) >> 31) != 0;
+ }
break;
}
--
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