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Bug 869072 - Test whether the upper 32 bits of a register are zeroed by loading

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an unsigned UINT32_MAX into a register and comparing with that, since x86's
cmp instruction's immediate field is a 32-bit signed field. r=sstangl
This commit is contained in:
Dan Gohman 2013-05-15 22:16:10 -04:00
parent f16fc9fb32
commit 36088f3cd7
1 changed files with 3 additions and 2 deletions
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5
js/src/ion/x64/MacroAssembler-x64.h
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@ -206,15 +206,16 @@ class MacroAssemblerX64 : public MacroAssemblerX86Shared
JS_ASSERT(src != dest);
JSValueShiftedTag tag = (JSValueShiftedTag)JSVAL_TYPE_TO_SHIFTED_TAG(type);
mov(ImmShiftedTag(tag), dest);
#ifdef DEBUG
if (type == JSVAL_TYPE_INT32 || type == JSVAL_TYPE_BOOLEAN) {
Label upper32BitsZeroed;
branchPtr(Assembler::BelowOrEqual, src, Imm32(UINT32_MAX), &upper32BitsZeroed);
movePtr(ImmWord(UINT32_MAX), dest);
branchPtr(Assembler::BelowOrEqual, src, dest, &upper32BitsZeroed);
breakpoint();
bind(&upper32BitsZeroed);
}
#endif
mov(ImmShiftedTag(tag), dest);
orq(src, dest);
}