[llvm] r350988 - [X86] Change some patterns that select MOVZX16rm8 to instead select MOVZX32rm8 and extract the subregister.

[Craig Topper via llvm-commits]

Author: ctopper
Date: Fri Jan 11 18:22:06 2019
New Revision: 350988

URL: http://llvm.org/viewvc/llvm-project?rev=350988&view=rev
Log:
[X86] Change some patterns that select MOVZX16rm8 to instead select MOVZX32rm8 and extract the subregister.

This should be a shorter encoding and is consistent with what we do for zext i8->i16

Modified:
    llvm/trunk/lib/Target/X86/X86InstrCompiler.td

Modified: llvm/trunk/lib/Target/X86/X86InstrCompiler.td
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86InstrCompiler.td?rev=350988&r1=350987&r2=350988&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86InstrCompiler.td (original)
+++ llvm/trunk/lib/Target/X86/X86InstrCompiler.td Fri Jan 11 18:22:06 2019
@@ -1276,7 +1276,8 @@ defm : CMOVmr<X86_COND_NO, CMOVO16rm , C
 // i1 stored in one byte in zero-extended form.
 // Upper bits cleanup should be executed before Store.
 def : Pat<(zextloadi8i1  addr:$src), (MOV8rm addr:$src)>;
-def : Pat<(zextloadi16i1 addr:$src), (MOVZX16rm8 addr:$src)>;
+def : Pat<(zextloadi16i1 addr:$src),
+          (EXTRACT_SUBREG (MOVZX32rm8 addr:$src), sub_16bit)>;
 def : Pat<(zextloadi32i1 addr:$src), (MOVZX32rm8 addr:$src)>;
 def : Pat<(zextloadi64i1 addr:$src),
           (SUBREG_TO_REG (i64 0), (MOVZX32rm8 addr:$src), sub_32bit)>;
@@ -1287,9 +1288,11 @@ def : Pat<(zextloadi64i1 addr:$src),
 // defined, avoiding partial-register updates.
 
 def : Pat<(extloadi8i1 addr:$src),   (MOV8rm      addr:$src)>;
-def : Pat<(extloadi16i1 addr:$src),  (MOVZX16rm8  addr:$src)>;
+def : Pat<(extloadi16i1 addr:$src),
+          (EXTRACT_SUBREG (MOVZX32rm8 addr:$src), sub_16bit)>;
 def : Pat<(extloadi32i1 addr:$src),  (MOVZX32rm8  addr:$src)>;
-def : Pat<(extloadi16i8 addr:$src),  (MOVZX16rm8  addr:$src)>;
+def : Pat<(extloadi16i8 addr:$src),
+          (EXTRACT_SUBREG (MOVZX32rm8 addr:$src), sub_16bit)>;
 def : Pat<(extloadi32i8 addr:$src),  (MOVZX32rm8  addr:$src)>;
 def : Pat<(extloadi32i16 addr:$src), (MOVZX32rm16 addr:$src)>;