[CSKY] Optimize conditional select with CLRT/CLRF

Reviewed By: zixuan-wu Differential Revision: https://reviews.llvm.org/D154409
llvm · Jul 4, 2023 · 3e6b80b · 3e6b80b
1 parent ef53ec9
commit 3e6b80b
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Showing 2 changed files with 8 additions and 5 deletions.
diff --git a/llvm/lib/Target/CSKY/CSKYInstrInfo.td b/llvm/lib/Target/CSKY/CSKYInstrInfo.td
@@ -1410,6 +1410,11 @@ defm : MOVTF32Pat1<setuge, setule, CMPHS32, MOVT32>;
 defm : MOVTF32Pat1<setult, setugt, CMPHS32, MOVF32>;
 defm : MOVTF32Pat1<setlt, setgt, CMPLT32, MOVT32>;
 defm : MOVTF32Pat1<setge, setle, CMPLT32, MOVF32>;
+
+def : Pat<(select CARRY:$ca, (i32 0), GPR:$other),
+          (CLRT32 CARRY:$ca, GPR:$other)>;
+def : Pat<(select CARRY:$ca, GPR:$other, (i32 0)),
+          (CLRF32 CARRY:$ca, GPR:$other)>;
 }
 
 // Constant materialize patterns.

diff --git a/llvm/test/CodeGen/CSKY/select.ll b/llvm/test/CodeGen/CSKY/select.ll
@@ -135,9 +135,8 @@ entry:
 define i32 @selectRI_0_if_true(i1 %c, i32 %q) {
 ; CHECK-LABEL: selectRI_0_if_true:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    movi16 a2, 0
 ; CHECK-NEXT:    btsti16 a0, 0
-; CHECK-NEXT:    movt32 a1, a2
+; CHECK-NEXT:    clrt32 a1
 ; CHECK-NEXT:    mov16 a0, a1
 ; CHECK-NEXT:    rts16
 ;
@@ -162,10 +161,9 @@ define i32 @selectRI_0_if_true(i1 %c, i32 %q) {
 define i32 @selectRI_0_if_false(i1 %c, i32 %q) {
 ; CHECK-LABEL: selectRI_0_if_false:
 ; CHECK:       # %bb.0:
-; CHECK-NEXT:    movi16 a2, 0
 ; CHECK-NEXT:    btsti16 a0, 0
-; CHECK-NEXT:    movt32 a2, a1
-; CHECK-NEXT:    mov16 a0, a2
+; CHECK-NEXT:    clrf32 a1
+; CHECK-NEXT:    mov16 a0, a1
 ; CHECK-NEXT:    rts16
 ;
 ; GENERIC-LABEL: selectRI_0_if_false: