[PPC][NFC] add an option to expose the bug in 74951

Author: Chen Zheng

llvm/test/CodeGen/PowerPC/pr74951.ll

@@ -1,5 +1,6 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 4
-; RUN: llc < %s -verify-machineinstrs -ppc-asm-full-reg-names -mtriple=powerpc64-ibm-aix-xcoff | FileCheck %s
+; RUN: llc < %s -start-before=codegenprepare -verify-machineinstrs -ppc-asm-full-reg-names \
+; RUN:   -mtriple=powerpc64-ibm-aix-xcoff | FileCheck %s
 
 %struct.anon = type { i32 }
 
@@ -11,26 +12,28 @@ define noundef signext i32 @main() {
 ; CHECK:       # %bb.0: # %entry
 ; CHECK-NEXT:    ld r3, L..C0(r2) # @b
 ; CHECK-NEXT:    lwz r3, 0(r3)
-; CHECK-NEXT:    extsw r4, r3
-; CHECK-NEXT:    neg r4, r4
-; CHECK-NEXT:    andi. r5, r3, 65535
-; CHECK-NEXT:    rldicl r4, r4, 1, 63
+; CHECK-NEXT:    andi. r4, r3, 65535
 ; CHECK-NEXT:    bne cr0, L..BB0_4
 ; CHECK-NEXT:  # %bb.1: # %lor.rhs.i.i
-; CHECK-NEXT:    xori r5, r4, 1
-; CHECK-NEXT:    cmpw r3, r5
+; CHECK-NEXT:    extsw r4, r3
+; CHECK-NEXT:    neg r5, r4
+; CHECK-NEXT:    rldicl r5, r5, 1, 63
+; CHECK-NEXT:    xori r5, r5, 1
+; CHECK-NEXT:    cmpw r4, r5
 ; CHECK-NEXT:    crnot 4*cr5+lt, eq
-; CHECK-NEXT:    li r3, 1
+; CHECK-NEXT:    li r4, 1
 ; CHECK-NEXT:    bc 12, 4*cr5+lt, L..BB0_3
 ; CHECK-NEXT:  # %bb.2: # %lor.rhs.i.i
-; CHECK-NEXT:    li r3, 0
+; CHECK-NEXT:    li r4, 0
 ; CHECK-NEXT:  L..BB0_3: # %lor.rhs.i.i
 ; CHECK-NEXT:    ld r5, L..C1(r2) # @g
-; CHECK-NEXT:    stb r3, 0(r5)
+; CHECK-NEXT:    stb r4, 0(r5)
 ; CHECK-NEXT:  L..BB0_4: # %g.exit
-; CHECK-NEXT:    ld r5, L..C1(r2) # @g
+; CHECK-NEXT:    ld r4, L..C1(r2) # @g
+; CHECK-NEXT:    neg r3, r3
+; CHECK-NEXT:    rldicl r5, r3, 1, 63
 ; CHECK-NEXT:    li r3, 0
-; CHECK-NEXT:    stb r4, 0(r5)
+; CHECK-NEXT:    stb r5, 0(r4)
 ; CHECK-NEXT:    blr
 entry:
   %0 = load i32, ptr @b, align 4