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Improve code generated for AllocInNewSpace. This is a commit of http://codereview.chromium.org/5512004 for Rodolph Perfetta.

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git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@5917 ce2b1a6d-e550-0410-aec6-3dcde31c8c00
This commit is contained in:
erik.corry@gmail.com 2010-12-06 09:59:08 +00:00
parent fb93e5bc36
commit bca83462d8
1 changed files with 80 additions and 51 deletions
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123
src/arm/macro-assembler-arm.cc
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@ -920,6 +920,7 @@ void MacroAssembler::AllocateInNewSpace(int object_size,
} }
ASSERT(!result.is(scratch1)); ASSERT(!result.is(scratch1));
ASSERT(!result.is(scratch2));
ASSERT(!scratch1.is(scratch2)); ASSERT(!scratch1.is(scratch2));
// Make object size into bytes. // Make object size into bytes.
@ -928,38 +929,55 @@ void MacroAssembler::AllocateInNewSpace(int object_size,
} }
ASSERT_EQ(0, object_size & kObjectAlignmentMask); ASSERT_EQ(0, object_size & kObjectAlignmentMask);
// Load address of new object into result and allocation top address into // Check relative positions of allocation top and limit addresses.
// scratch1. // The values must be adjacent in memory to allow the use of LDM.
// Also, assert that the registers are numbered such that the values
// are loaded in the correct order.
ExternalReference new_space_allocation_top = ExternalReference new_space_allocation_top =
ExternalReference::new_space_allocation_top_address(); ExternalReference::new_space_allocation_top_address();
mov(scratch1, Operand(new_space_allocation_top)); ExternalReference new_space_allocation_limit =
ExternalReference::new_space_allocation_limit_address();
intptr_t top =
reinterpret_cast<intptr_t>(new_space_allocation_top.address());
intptr_t limit =
reinterpret_cast<intptr_t>(new_space_allocation_limit.address());
ASSERT((limit - top) == kPointerSize);
ASSERT(result.code() < ip.code());
// Set up allocation top address and object size registers.
Register topaddr = scratch1;
Register obj_size_reg = scratch2;
mov(topaddr, Operand(new_space_allocation_top));
mov(obj_size_reg, Operand(object_size));
// This code stores a temporary value in ip. This is OK, as the code below
// does not need ip for implicit literal generation.
if ((flags & RESULT_CONTAINS_TOP) == 0) { if ((flags & RESULT_CONTAINS_TOP) == 0) {
ldr(result, MemOperand(scratch1)); // Load allocation top into result and allocation limit into ip.
} else if (FLAG_debug_code) { ldm(ia, topaddr, result.bit() | ip.bit());
// Assert that result actually contains top on entry. scratch2 is used } else {
// immediately below so this use of scratch2 does not cause difference with if (FLAG_debug_code) {
// Assert that result actually contains top on entry. ip is used
// immediately below so this use of ip does not cause difference with
// respect to register content between debug and release mode. // respect to register content between debug and release mode.
ldr(scratch2, MemOperand(scratch1)); ldr(ip, MemOperand(topaddr));
cmp(result, scratch2); cmp(result, ip);
Check(eq, "Unexpected allocation top"); Check(eq, "Unexpected allocation top");
} }
// Load allocation limit into ip. Result already contains allocation top.
ldr(ip, MemOperand(topaddr, limit - top));
}
// Calculate new top and bail out if new space is exhausted. Use result // Calculate new top and bail out if new space is exhausted. Use result
// to calculate the new top. // to calculate the new top.
ExternalReference new_space_allocation_limit = add(scratch2, result, Operand(obj_size_reg));
ExternalReference::new_space_allocation_limit_address(); cmp(scratch2, Operand(ip));
mov(scratch2, Operand(new_space_allocation_limit));
ldr(scratch2, MemOperand(scratch2));
add(result, result, Operand(object_size));
cmp(result, Operand(scratch2));
b(hi, gc_required); b(hi, gc_required);
str(result, MemOperand(scratch1)); str(scratch2, MemOperand(topaddr));
// Tag and adjust back to start of new object. // Tag object if requested.
if ((flags & TAG_OBJECT) != 0) { if ((flags & TAG_OBJECT) != 0) {
sub(result, result, Operand(object_size - kHeapObjectTag)); add(result, result, Operand(kHeapObjectTag));
} else {
sub(result, result, Operand(object_size));
} }
} }
@ -982,52 +1000,63 @@ void MacroAssembler::AllocateInNewSpace(Register object_size,
} }
ASSERT(!result.is(scratch1)); ASSERT(!result.is(scratch1));
ASSERT(!result.is(scratch2));
ASSERT(!scratch1.is(scratch2)); ASSERT(!scratch1.is(scratch2));
// Load address of new object into result and allocation top address into // Check relative positions of allocation top and limit addresses.
// scratch1. // The values must be adjacent in memory to allow the use of LDM.
// Also, assert that the registers are numbered such that the values
// are loaded in the correct order.
ExternalReference new_space_allocation_top = ExternalReference new_space_allocation_top =
ExternalReference::new_space_allocation_top_address(); ExternalReference::new_space_allocation_top_address();
mov(scratch1, Operand(new_space_allocation_top)); ExternalReference new_space_allocation_limit =
ExternalReference::new_space_allocation_limit_address();
intptr_t top =
reinterpret_cast<intptr_t>(new_space_allocation_top.address());
intptr_t limit =
reinterpret_cast<intptr_t>(new_space_allocation_limit.address());
ASSERT((limit - top) == kPointerSize);
ASSERT(result.code() < ip.code());
// Set up allocation top address.
Register topaddr = scratch1;
mov(topaddr, Operand(new_space_allocation_top));
// This code stores a temporary value in ip. This is OK, as the code below
// does not need ip for implicit literal generation.
if ((flags & RESULT_CONTAINS_TOP) == 0) { if ((flags & RESULT_CONTAINS_TOP) == 0) {
ldr(result, MemOperand(scratch1)); // Load allocation top into result and allocation limit into ip.
} else if (FLAG_debug_code) { ldm(ia, topaddr, result.bit() | ip.bit());
// Assert that result actually contains top on entry. scratch2 is used } else {
// immediately below so this use of scratch2 does not cause difference with if (FLAG_debug_code) {
// Assert that result actually contains top on entry. ip is used
// immediately below so this use of ip does not cause difference with
// respect to register content between debug and release mode. // respect to register content between debug and release mode.
ldr(scratch2, MemOperand(scratch1)); ldr(ip, MemOperand(topaddr));
cmp(result, scratch2); cmp(result, ip);
Check(eq, "Unexpected allocation top"); Check(eq, "Unexpected allocation top");
} }
// Load allocation limit into ip. Result already contains allocation top.
ldr(ip, MemOperand(topaddr, limit - top));
}
// Calculate new top and bail out if new space is exhausted. Use result // Calculate new top and bail out if new space is exhausted. Use result
// to calculate the new top. Object size is in words so a shift is required to // to calculate the new top. Object size may be in words so a shift is
// get the number of bytes // required to get the number of bytes.
ExternalReference new_space_allocation_limit =
ExternalReference::new_space_allocation_limit_address();
mov(scratch2, Operand(new_space_allocation_limit));
ldr(scratch2, MemOperand(scratch2));
if ((flags & SIZE_IN_WORDS) != 0) { if ((flags & SIZE_IN_WORDS) != 0) {
add(result, result, Operand(object_size, LSL, kPointerSizeLog2)); add(scratch2, result, Operand(object_size, LSL, kPointerSizeLog2));
} else { } else {
add(result, result, Operand(object_size)); add(scratch2, result, Operand(object_size));
} }
cmp(result, Operand(scratch2)); cmp(scratch2, Operand(ip));
b(hi, gc_required); b(hi, gc_required);
// Update allocation top. result temporarily holds the new top. // Update allocation top. result temporarily holds the new top.
if (FLAG_debug_code) { if (FLAG_debug_code) {
tst(result, Operand(kObjectAlignmentMask)); tst(scratch2, Operand(kObjectAlignmentMask));
Check(eq, "Unaligned allocation in new space"); Check(eq, "Unaligned allocation in new space");
} }
str(result, MemOperand(scratch1)); str(scratch2, MemOperand(topaddr));
// Adjust back to start of new object.
if ((flags & SIZE_IN_WORDS) != 0) {
sub(result, result, Operand(object_size, LSL, kPointerSizeLog2));
} else {
sub(result, result, Operand(object_size));
}
// Tag object if requested. // Tag object if requested.
if ((flags & TAG_OBJECT) != 0) { if ((flags & TAG_OBJECT) != 0) {