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Bug 843015: The Extended ldr instructions have a smaller maximum offset (255). Actually respect these limits. Also use paretheses correctly (r=sstangl)

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This commit is contained in:
Marty Rosenberg 2013-02-24 00:40:28 -05:00
parent 48e7cb1722
commit a52453d3d6
1 changed files with 15 additions and 6 deletions
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21
js/src/assembler/assembler/ARMAssembler.cpp
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@ -327,19 +327,28 @@ void ARMAssembler::dataTransferN(bool isLoad, bool isSigned, int size, RegisterI
offset = - offset;
posOffset = false;
}
if (offset <= 0xfff) {
// max_ldr is also a mask.
int max_ldr = 0xfff;
int ldr_bits = 12;
if (size == 16 || (size == 8 && isSigned)) {
max_ldr = 0xff;
ldr_bits = 8;
}
if (offset <= max_ldr) {
// LDR rd, [rb, #+offset]
mem_imm_off(isLoad, isSigned, size, posOffset, rt, base, offset);
} else if (offset <= 0xfffff) {
} else if (offset <= ((max_ldr << 8) | 0xff)) {
// Add upper bits of offset to the base, and store the result into the temp register.
if (posOffset) {
add_r(ARMRegisters::S0, base, OP2_IMM | (offset >> 12) | getOp2RotLSL(12));
add_r(ARMRegisters::S0, base, OP2_IMM | (offset >> ldr_bits) | getOp2RotLSL(ldr_bits));
} else {
sub_r(ARMRegisters::S0, base, OP2_IMM | (offset >> 12) | getOp2RotLSL(12));
sub_r(ARMRegisters::S0, base, OP2_IMM | (offset >> ldr_bits) | getOp2RotLSL(ldr_bits));
}
// Load using the lower bits of the offset.
// Load using the lower bits of the offset, using max_ldr as a mask.
mem_imm_off(isLoad, isSigned, size, posOffset, rt,
ARMRegisters::S0, (offset & 0xfff));
ARMRegisters::S0, (offset & max_ldr));
} else {
// For even bigger offsets, load the entire offset into a register, then do an
// indexed load using the base register and the index register.