[llvm] [PowerPC] Lower UCMP and SCMP directly to setb instead of matching the DAG shape (PR #206282)

[zhijian lin via llvm-commits]

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@@ -10,6 +11,12 @@ define i8 @scmp_8_8(i8 signext %x, i8 signext %y) nounwind {
 ; CHECK-NEXT:    rldicl 5, 5, 1, 63
 ; CHECK-NEXT:    isellt 3, 3, 5
 ; CHECK-NEXT:    blr
+;
+; P9-LABEL: scmp_8_8:
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diggerlin wrote:

even without your patch , I think llvm already generate the asm 

; CHECK-PWR9-LABEL: scmp_8_8:
; CHECK-PWR9:       # %bb.0:
; CHECK-PWR9-NEXT:    cmpw 3, 4
; CHECK-PWR9-NEXT:    setb 3, 0
; CHECK-PWR9-NEXT:    blr

can create a base commit having the command line 
 RUN: llc -mtriple=ppc64le-unknown-unknown %s -o - | FileCheck %s --check-prefix=CHECK
; RUN: llc -mtriple=ppc64le-unknown-unknown -mcpu=pwr9 %s -o - | FileCheck %s --check-prefix=P9 

in your test case but without your fix, 

so we compare what change after your fix

https://github.com/llvm/llvm-project/pull/206282