[UpdateTestChecks][PowerPC] Avoid empty string when scrubbing loop comments

[jsji]

Summary

SCRUB_LOOP_COMMENT_RE was introduced in https://reviews.llvm.org/D31285
This works for some loops.

However, we may generate lines with loop comments only.
And since we don't scrub leading white spaces, this will leave an empty
line there, and FileCheck will complain it.

eg: llvm/test/CodeGen/PowerPC/PR35812-neg-cmpxchg.ll:27:15:
error: found empty check string with prefix 'CHECK:'
; CHECK-NEXT:

This prevented us from using the update_llc_test_checks.py for quite some cases.

We should still keep the comment token there, so that we can safely
scrub the loop comment without breaking FileCheck.

[lebedev.ri]

llvm/utils/UpdateTestChecks/asm.py

218 ↗

(On Diff #207145)

Does the comment need updating?

[jsji]

Update the comments.

[lebedev.ri]

Makes sense

llvm/trunk/test/CodeGen/PowerPC/PR35812-neg-cmpxchg.ll

 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; Make sure that a negative value for the compare-and-swap is zero extended
 ; from i8/i16 to i32 since it will be compared for equality.
 ; RUN: llc -mtriple=powerpc64le-linux-gnu -verify-machineinstrs < %s | FileCheck %s
 ; RUN: llc -mtriple=powerpc64le-linux-gnu -mcpu=pwr7 -verify-machineinstrs < %s | FileCheck %s --check-prefix=CHECK-P7
 
 @str = private unnamed_addr constant [46 x i8] c"FAILED: __atomic_compare_exchange_n() failed.\00"
 @str.1 = private unnamed_addr constant [59 x i8] c"FAILED: __atomic_compare_exchange_n() set the wrong value.\00"
 @str.2 = private unnamed_addr constant [7 x i8] c"PASSED\00"
 
 define signext i32 @main() {
 ; CHECK-LABEL: main:
-; CHECK:    li 3, -32477
-; CHECK:    li 6, 234
-; CHECK:    sth 3, 46(1)
-; CHECK:    lis 3, 0
-; CHECK:    ori 4, 3, 33059
-; CHECK:    sync
-; CHECK:  .LBB0_1: # %L.entry
-; CHECK:    lharx 3, 0, 5
-; CHECK:    cmpw 4, 3
-; CHECK:    bne 0, .LBB0_3
-; CHECK:    sthcx. 6, 0, 5
-; CHECK:    bne 0, .LBB0_1
-; CHECK:    b .LBB0_4
-; CHECK:  .LBB0_3: # %L.entry
-; CHECK:    sthcx. 3, 0, 5
-; CHECK:  .LBB0_4: # %L.entry
-; CHECK:    cmplwi 3, 33059
-; CHECK:    lwsync
-; CHECK:    lhz 3, 46(1)
-; CHECK:    cmplwi 3, 234
+; CHECK:       # %bb.0: # %L.entry
+; CHECK-NEXT:    mflr 0
+; CHECK-NEXT:    std 0, 16(1)
+; CHECK-NEXT:    stdu 1, -48(1)
+; CHECK-NEXT:    .cfi_def_cfa_offset 48
+; CHECK-NEXT:    .cfi_offset lr, 16
+; CHECK-NEXT:    li 3, -32477
+; CHECK-NEXT:    li 6, 234
+; CHECK-NEXT:    addi 5, 1, 46
+; CHECK-NEXT:    sth 3, 46(1)
+; CHECK-NEXT:    lis 3, 0
+; CHECK-NEXT:    ori 4, 3, 33059
+; CHECK-NEXT:    sync
+; CHECK-NEXT:  .LBB0_1: # %L.entry
+; CHECK-NEXT:    #
+; CHECK-NEXT:    lharx 3, 0, 5
+; CHECK-NEXT:    cmpw 4, 3
+; CHECK-NEXT:    bne 0, .LBB0_3
+; CHECK-NEXT:  # %bb.2: # %L.entry
+; CHECK-NEXT:    #
+; CHECK-NEXT:    sthcx. 6, 0, 5
+; CHECK-NEXT:    bne 0, .LBB0_1
+; CHECK-NEXT:    b .LBB0_4
+; CHECK-NEXT:  .LBB0_3: # %L.entry
+; CHECK-NEXT:    sthcx. 3, 0, 5
+; CHECK-NEXT:  .LBB0_4: # %L.entry
+; CHECK-NEXT:    cmplwi 3, 33059
+; CHECK-NEXT:    lwsync
+; CHECK-NEXT:    bne 0, .LBB0_7
+; CHECK-NEXT:  # %bb.5: # %L.B0000
+; CHECK-NEXT:    lhz 3, 46(1)
+; CHECK-NEXT:    cmplwi 3, 234
+; CHECK-NEXT:    bne 0, .LBB0_8
+; CHECK-NEXT:  # %bb.6: # %L.B0001
+; CHECK-NEXT:    addis 3, 2, .Lstr.2@toc@ha
+; CHECK-NEXT:    addi 3, 3, .Lstr.2@toc@l
+; CHECK-NEXT:    bl puts
+; CHECK-NEXT:    nop
+; CHECK-NEXT:    li 3, 0
+; CHECK-NEXT:    b .LBB0_10
+; CHECK-NEXT:  .LBB0_7: # %L.B0003
+; CHECK-NEXT:    addis 3, 2, .Lstr@toc@ha
+; CHECK-NEXT:    addi 3, 3, .Lstr@toc@l
+; CHECK-NEXT:    b .LBB0_9
+; CHECK-NEXT:  .LBB0_8: # %L.B0005
+; CHECK-NEXT:    addis 3, 2, .Lstr.1@toc@ha
+; CHECK-NEXT:    addi 3, 3, .Lstr.1@toc@l
+; CHECK-NEXT:  .LBB0_9: # %L.B0003
+; CHECK-NEXT:    bl puts
+; CHECK-NEXT:    nop
+; CHECK-NEXT:    li 3, 1
+; CHECK-NEXT:  .LBB0_10: # %L.B0003
+; CHECK-NEXT:    addi 1, 1, 48
+; CHECK-NEXT:    ld 0, 16(1)
+; CHECK-NEXT:    mtlr 0
+; CHECK-NEXT:    blr
 ;
 ; CHECK-P7-LABEL: main:
-; CHECK-P7:    li 3, -32477
-; CHECK-P7:    lis 5, 0
-; CHECK-P7:    li 7, 0
-; CHECK-P7:    sth 3, 46(1)
-; CHECK-P7:    li 6, 234
-; CHECK-P7:    ori 5, 5, 33059
-; CHECK-P7:    rlwinm 3, 4, 3, 27, 27
-; CHECK-P7:    ori 7, 7, 65535
-; CHECK-P7:    sync
-; CHECK-P7:    slw 6, 6, 3
-; CHECK-P7:    slw 8, 5, 3
-; CHECK-P7:    slw 5, 7, 3
-; CHECK-P7:    rldicr 4, 4, 0, 61
-; CHECK-P7:    and 7, 6, 5
-; CHECK-P7:    and 8, 8, 5
-; CHECK-P7:  .LBB0_1: # %L.entry
-; CHECK-P7:    lwarx 9, 0, 4
-; CHECK-P7:    and 6, 9, 5
-; CHECK-P7:    cmpw 6, 8
-; CHECK-P7:    bne 0, .LBB0_3
-; CHECK-P7:    andc 9, 9, 5
-; CHECK-P7:    or 9, 9, 7
-; CHECK-P7:    stwcx. 9, 0, 4
-; CHECK-P7:    bne 0, .LBB0_1
-; CHECK-P7:    b .LBB0_4
-; CHECK-P7:  .LBB0_3: # %L.entry
-; CHECK-P7:    stwcx. 9, 0, 4
-; CHECK-P7:  .LBB0_4: # %L.entry
-; CHECK-P7:    srw 3, 6, 3
-; CHECK-P7:    lwsync
-; CHECK-P7:    cmplwi 3, 33059
-; CHECK-P7:    lhz 3, 46(1)
-; CHECK-P7:    cmplwi 3, 234
+; CHECK-P7:       # %bb.0: # %L.entry
+; CHECK-P7-NEXT:    mflr 0
+; CHECK-P7-NEXT:    std 0, 16(1)
+; CHECK-P7-NEXT:    stdu 1, -48(1)
+; CHECK-P7-NEXT:    .cfi_def_cfa_offset 48
+; CHECK-P7-NEXT:    .cfi_offset lr, 16
+; CHECK-P7-NEXT:    li 3, -32477
+; CHECK-P7-NEXT:    lis 5, 0
+; CHECK-P7-NEXT:    addi 4, 1, 46
+; CHECK-P7-NEXT:    li 7, 0
+; CHECK-P7-NEXT:    sth 3, 46(1)
+; CHECK-P7-NEXT:    li 6, 234
+; CHECK-P7-NEXT:    ori 5, 5, 33059
+; CHECK-P7-NEXT:    rlwinm 3, 4, 3, 27, 27
+; CHECK-P7-NEXT:    ori 7, 7, 65535
+; CHECK-P7-NEXT:    sync
+; CHECK-P7-NEXT:    slw 6, 6, 3
+; CHECK-P7-NEXT:    slw 8, 5, 3
+; CHECK-P7-NEXT:    slw 5, 7, 3
+; CHECK-P7-NEXT:    rldicr 4, 4, 0, 61
+; CHECK-P7-NEXT:    and 7, 6, 5
+; CHECK-P7-NEXT:    and 8, 8, 5
+; CHECK-P7-NEXT:  .LBB0_1: # %L.entry
+; CHECK-P7-NEXT:    #
+; CHECK-P7-NEXT:    lwarx 9, 0, 4
+; CHECK-P7-NEXT:    and 6, 9, 5
+; CHECK-P7-NEXT:    cmpw 6, 8
+; CHECK-P7-NEXT:    bne 0, .LBB0_3
+; CHECK-P7-NEXT:  # %bb.2: # %L.entry
+; CHECK-P7-NEXT:    #
+; CHECK-P7-NEXT:    andc 9, 9, 5
+; CHECK-P7-NEXT:    or 9, 9, 7
+; CHECK-P7-NEXT:    stwcx. 9, 0, 4
+; CHECK-P7-NEXT:    bne 0, .LBB0_1
+; CHECK-P7-NEXT:    b .LBB0_4
+; CHECK-P7-NEXT:  .LBB0_3: # %L.entry
+; CHECK-P7-NEXT:    stwcx. 9, 0, 4
+; CHECK-P7-NEXT:  .LBB0_4: # %L.entry
+; CHECK-P7-NEXT:    srw 3, 6, 3
+; CHECK-P7-NEXT:    lwsync
+; CHECK-P7-NEXT:    cmplwi 3, 33059
+; CHECK-P7-NEXT:    bne 0, .LBB0_7
+; CHECK-P7-NEXT:  # %bb.5: # %L.B0000
+; CHECK-P7-NEXT:    lhz 3, 46(1)
+; CHECK-P7-NEXT:    cmplwi 3, 234
+; CHECK-P7-NEXT:    bne 0, .LBB0_8
+; CHECK-P7-NEXT:  # %bb.6: # %L.B0001
+; CHECK-P7-NEXT:    addis 3, 2, .Lstr.2@toc@ha
+; CHECK-P7-NEXT:    addi 3, 3, .Lstr.2@toc@l
+; CHECK-P7-NEXT:    bl puts
+; CHECK-P7-NEXT:    nop
+; CHECK-P7-NEXT:    li 3, 0
+; CHECK-P7-NEXT:    b .LBB0_10
+; CHECK-P7-NEXT:  .LBB0_7: # %L.B0003
+; CHECK-P7-NEXT:    addis 3, 2, .Lstr@toc@ha
+; CHECK-P7-NEXT:    addi 3, 3, .Lstr@toc@l
+; CHECK-P7-NEXT:    b .LBB0_9
+; CHECK-P7-NEXT:  .LBB0_8: # %L.B0005
+; CHECK-P7-NEXT:    addis 3, 2, .Lstr.1@toc@ha
+; CHECK-P7-NEXT:    addi 3, 3, .Lstr.1@toc@l
+; CHECK-P7-NEXT:  .LBB0_9: # %L.B0003
+; CHECK-P7-NEXT:    bl puts
+; CHECK-P7-NEXT:    nop
+; CHECK-P7-NEXT:    li 3, 1
+; CHECK-P7-NEXT:  .LBB0_10: # %L.B0003
+; CHECK-P7-NEXT:    addi 1, 1, 48
+; CHECK-P7-NEXT:    ld 0, 16(1)
+; CHECK-P7-NEXT:    mtlr 0
+; CHECK-P7-NEXT:    blr
 L.entry:
   %value.addr = alloca i16, align 2
   store i16 -32477, i16* %value.addr, align 2
   %0 = cmpxchg i16* %value.addr, i16 -32477, i16 234 seq_cst seq_cst
   %1 = extractvalue { i16, i1 } %0, 1
   br i1 %1, label %L.B0000, label %L.B0003
 
 L.B0003:                                          ; preds = %L.entry

llvm/trunk/utils/UpdateTestChecks/asm.py

def scrub_asm_hexagon(asm, args):
   return asm
 
 def scrub_asm_powerpc(asm, args):
   # Scrub runs of whitespace out of the assembly, but leave the leading
   # whitespace in place.
   asm = common.SCRUB_WHITESPACE_RE.sub(r' ', asm)
   # Expand the tabs used for indentation.
   asm = string.expandtabs(asm, 2)
-  # Stripe unimportant comments
-  asm = SCRUB_LOOP_COMMENT_RE.sub(r'', asm)
+  # Stripe unimportant comments, but leave the token '#' in place.
+  asm = SCRUB_LOOP_COMMENT_RE.sub(r'#', asm)
   # Strip trailing whitespace.
   asm = common.SCRUB_TRAILING_WHITESPACE_RE.sub(r'', asm)
   return asm
 
 def scrub_asm_mips(asm, args):
   # Scrub runs of whitespace out of the assembly, but leave the leading
   # whitespace in place.
   asm = common.SCRUB_WHITESPACE_RE.sub(r' ', asm)