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Reinstate the x86-64 portion of r55190. When doing extloads into 

64-bit registers from 16-bit and smaller memory locations, prefer
instructions that define the entire 64-bit register, to avoid
partial-register updates.

llvm-svn: 55422
This commit is contained in:
Dan Gohman 2008-08-27 17:33:15 +00:00
parent 3a3a52de58
commit 7f2777e8d2
1 changed files with 8 additions and 9 deletions
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17
llvm/lib/Target/X86/X86Instr64bit.td
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@ -1254,15 +1254,14 @@ def : Pat<(i64 (zext GR32:$src)),
def : Pat<(zextloadi64i1 addr:$src), (MOVZX64rm8 addr:$src)>;
// extload
def : Pat<(extloadi64i1 addr:$src),
(INSERT_SUBREG (i64 (IMPLICIT_DEF)), (MOV8rm addr:$src),
x86_subreg_8bit)>;
def : Pat<(extloadi64i8 addr:$src),
(INSERT_SUBREG (i64 (IMPLICIT_DEF)), (MOV8rm addr:$src),
x86_subreg_8bit)>;
def : Pat<(extloadi64i16 addr:$src),
(INSERT_SUBREG (i64 (IMPLICIT_DEF)), (MOV16rm addr:$src),
x86_subreg_16bit)>;
// When extloading from 16-bit and smaller memory locations into 64-bit registers,
// use zero-extending loads so that the entire 64-bit register is defined, avoiding
// partial-register updates.
def : Pat<(extloadi64i1 addr:$src), (MOVZX64rm8 addr:$src)>;
def : Pat<(extloadi64i8 addr:$src), (MOVZX64rm8 addr:$src)>;
def : Pat<(extloadi64i16 addr:$src), (MOVZX64rm16 addr:$src)>;
// For other extloads, use subregs, since the high contents of the register are
// defined after an extload.
def : Pat<(extloadi64i32 addr:$src),
(INSERT_SUBREG (i64 (IMPLICIT_DEF)), (MOV32rm addr:$src),
x86_subreg_32bit)>;