[PowerPC] Replace cntlz[.] with cntlzw[.]

[trixirt]

Summary

cntlz is the old POWER mnemonic.
cntlzw is the PowerPC mnemonic.

This change fixes an issue when -no-integrated-as.
The opcode cntlz is unrecognized by gas

Change PowerPC tests to reflect the insn change from cntlz to cntlzw.

Alias the POWER mnemonic cntlz[.] to the PowerPC mnemonic cntlzw[.]
This is done for because the POWER cntlz mnemonic has be used in llvm for
a very long time. We need to make sure that assembly programs
that are using the cntlz[.] do not break with this change.

Add assembly test to verify cntlz[.] is encoded correctly.

[hfinkel]

I think this is fine, although given that we've accepted the older form for a long time (and it was apparently in use, at least on some older Darwin systems), we should be kind to our users and continue to accept it as an alias. Please add the InstAlias defs and associated parsing tests (set InstAlias's Emit parameter to 0).

Also, as best I can tell from https://llvm.org/bugs/show_bug.cgi?id=1095 and http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20070115/042738.html, Darwin also wanted the newer mnemonic spelling. This is confusing, given that we have old tests specifically for the old form. Bill, if you can remember from that long ago, can you comment on what we should do here for Darwin?

[hfinkel]

[+David Fang; maybe you can comment on Darwin]

• Original Message -----

From: [e-mail]
To: [e-mail], [e-mail], [e-mail]
Cc: [e-mail]
Sent: Friday, September 25, 2015 7:44:12 AM
Subject: Re: [PATCH] D13142: [PowerPC] Replace cntlz[.] with cntlzw[.]

hfinkel added a comment.

I think this is fine, although given that we've accepted the older
form for a long time (and it was apparently in use, at least on some
older Darwin systems), we should be kind to our users and continue
to accept it as an alias. Please add the InstAlias defs and
associated parsing tests (set InstAlias's Emit parameter to 0).

Also, as best I can tell from
https://llvm.org/bugs/show_bug.cgi?id=1095 and
http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20070115/042738.html,
Darwin also wanted the newer mnemonic spelling. This is confusing,
given that we have old tests specifically for the old form. Bill, if
you can remember from that long ago, can you comment on what we
should do here for Darwin?

http://reviews.llvm.org/D13142

[void]

Unfortunately, I only vaguely recall this patch. Is there a reason not to
have support for both? I don't think we support POWER in LLVM though (I
could be wrong there) ... You may need to ask one of the ppc experts here.

[trixirt]

Added alias back to old cntlz mnemonic.
So old, stand alone assembly programs will still work.

The code generation will only use the PowerPC mnemonic.
No obvious flag to hang the POWER variant off of.

A non llvm program using the generated assembly would break if it only handled the
POWER variant.

[hfinkel]

LGTM.

lib/Target/PowerPC/PPCInstrInfo.td

3888

I'd specifically mention in the comment that the reason we're supporting this particular POWER alias is because LLVM used only this form for many years.

[trixirt]

improve commit log to explain long use of cntlz is why this POWER mnemonic is supported.

Cleanup whitespace problems in tests.

[hfinkel]

r251489.

lib/Target/PowerPC/PPCInstrInfo.td

 
 def : InstAlias<"rotlwi $rA, $rS, $n", (RLWINM gprc:$rA, gprc:$rS, u5imm:$n, 0, 31)>;
 def : InstAlias<"rotlwi. $rA, $rS, $n", (RLWINMo gprc:$rA, gprc:$rS, u5imm:$n, 0, 31)>;
 def : InstAlias<"rotlw $rA, $rS, $rB", (RLWNM gprc:$rA, gprc:$rS, gprc:$rB, 0, 31)>;
 def : InstAlias<"rotlw. $rA, $rS, $rB", (RLWNMo gprc:$rA, gprc:$rS, gprc:$rB, 0, 31)>;
 def : InstAlias<"clrlwi $rA, $rS, $n", (RLWINM gprc:$rA, gprc:$rS, 0, u5imm:$n, 31)>;
 def : InstAlias<"clrlwi. $rA, $rS, $n", (RLWINMo gprc:$rA, gprc:$rS, 0, u5imm:$n, 31)>;
 
-def : InstAlias<"cntlz $rA, $rS", (CNTLZW gprc:$rA, gprc:$rS)>;
-def : InstAlias<"cntlz. $rA, $rS", (CNTLZWo gprc:$rA, gprc:$rS)>;
+def : InstAlias<"cntlzw $rA, $rS", (CNTLZW gprc:$rA, gprc:$rS)>;
+def : InstAlias<"cntlzw. $rA, $rS", (CNTLZWo gprc:$rA, gprc:$rS)>;
+// The POWER variant
+def : MnemonicAlias<"cntlz",  "cntlzw">;
+def : MnemonicAlias<"cntlz.", "cntlzw.">;
 
 def EXTLDI : PPCAsmPseudo<"extldi $rA, $rS, $n, $b",
                           (ins g8rc:$rA, g8rc:$rS, u6imm:$n, u6imm:$b)>;
 def EXTLDIo : PPCAsmPseudo<"extldi. $rA, $rS, $n, $b",
                            (ins g8rc:$rA, g8rc:$rS, u6imm:$n, u6imm:$b)>;
 def EXTRDI : PPCAsmPseudo<"extrdi $rA, $rS, $n, $b",
                           (ins g8rc:$rA, g8rc:$rS, u6imm:$n, u6imm:$b)>;
 def EXTRDIo : PPCAsmPseudo<"extrdi. $rA, $rS, $n, $b",

test/CodeGen/PowerPC/cttz.ll

 ; Make sure this testcase does not use ctpop
 ; RUN: llc < %s -march=ppc32 -mcpu=g5 | FileCheck %s
 
 declare i32 @llvm.cttz.i32(i32, i1)
 
 define i32 @bar(i32 %x) {
 entry:
 ; CHECK: @bar
-; CHECK: cntlz
+; CHECK: cntlzw
         %tmp.1 = call i32 @llvm.cttz.i32( i32 %x, i1 true )              ; <i32> [#uses=1]
         ret i32 %tmp.1
 }
 

test/CodeGen/PowerPC/long-compare.ll

-; RUN: llc < %s -march=ppc32 | grep cntlz
+; RUN: llc < %s -march=ppc32 | grep cntlzw
 ; RUN: llc < %s -march=ppc32 | not grep xori 
 ; RUN: llc < %s -march=ppc32 | not grep "li "
 ; RUN: llc < %s -march=ppc32 | not grep "mr "
 
 define i1 @test(i64 %x) {
   %tmp = icmp ult i64 %x, 4294967296
   ret i1 %tmp
 }

test/CodeGen/PowerPC/seteq-0.ll

 ; RUN: llc < %s -march=ppc32 -mtriple=powerpc-apple-darwin8 | FileCheck %s
 
 define i32 @eq0(i32 %a) {
         %tmp.1 = icmp eq i32 %a, 0              ; <i1> [#uses=1]
         %tmp.2 = zext i1 %tmp.1 to i32          ; <i32> [#uses=1]
         ret i32 %tmp.2
 
-; CHECK: cntlz [[REG:r[0-9]+]], r3
+; CHECK: cntlzw [[REG:r[0-9]+]], r3
 ; CHECK: rlwinm r3, [[REG]], 27, 31, 31
 ; CHECK: blr
 }
 

test/MC/Disassembler/PowerPC/ppc64-encoding.txt

 0x7c 0x62 0x07 0x75
 
 # CHECK: extsh 2, 3                      
 0x7c 0x62 0x07 0x34
 
 # CHECK: extsh. 2, 3                     
 0x7c 0x62 0x07 0x35
 
-# CHECK: cntlz 2, 3
+# CHECK: cntlzw 2, 3
 0x7c 0x62 0x00 0x34
 
-# CHECK: cntlz. 2, 3
+# CHECK: cntlzw. 2, 3
 0x7c 0x62 0x00 0x35
 
 # CHECK: popcntw 2, 3                    
 0x7c 0x62 0x02 0xf4
 
 # CHECK: extsw 2, 3                      
 0x7c 0x62 0x07 0xb4
 

test/MC/Disassembler/PowerPC/ppc64le-encoding.txt

 0x75 0x07 0x62 0x7c
 
 # CHECK: extsh 2, 3
 0x34 0x07 0x62 0x7c
 
 # CHECK: extsh. 2, 3
 0x35 0x07 0x62 0x7c
 
-# CHECK: cntlz 2, 3
+# CHECK: cntlzw 2, 3
 0x34 0x00 0x62 0x7c
 
-# CHECK: cntlz. 2, 3
+# CHECK: cntlzw. 2, 3
 0x35 0x00 0x62 0x7c
 
 # CHECK: popcntw 2, 3
 0xf4 0x02 0x62 0x7c
 
 # CHECK: extsw 2, 3
 0xb4 0x07 0x62 0x7c
 

test/MC/PowerPC/ppc64-encoding.s

             extsb. 2, 3
 # CHECK-BE: extsh 2, 3                      # encoding: [0x7c,0x62,0x07,0x34]
 # CHECK-LE: extsh 2, 3                      # encoding: [0x34,0x07,0x62,0x7c]
             extsh 2, 3
 # CHECK-BE: extsh. 2, 3                     # encoding: [0x7c,0x62,0x07,0x35]
 # CHECK-LE: extsh. 2, 3                     # encoding: [0x35,0x07,0x62,0x7c]
             extsh. 2, 3
 
-# CHECK-BE: cntlz 2, 3                     # encoding: [0x7c,0x62,0x00,0x34]
-# CHECK-LE: cntlz 2, 3                     # encoding: [0x34,0x00,0x62,0x7c]
+# CHECK-BE: cntlzw 2, 3                     # encoding: [0x7c,0x62,0x00,0x34]
+# CHECK-LE: cntlzw 2, 3                     # encoding: [0x34,0x00,0x62,0x7c]
             cntlzw 2, 3
-# CHECK-BE: cntlz. 2, 3                    # encoding: [0x7c,0x62,0x00,0x35]
-# CHECK-LE: cntlz. 2, 3                    # encoding: [0x35,0x00,0x62,0x7c]
+# CHECK-BE: cntlzw. 2, 3                    # encoding: [0x7c,0x62,0x00,0x35]
+# CHECK-LE: cntlzw. 2, 3                    # encoding: [0x35,0x00,0x62,0x7c]
             cntlzw. 2, 3
-# CHECK-BE: cntlz 2, 3                     # encoding: [0x7c,0x62,0x00,0x34]
-# CHECK-LE: cntlz 2, 3                     # encoding: [0x34,0x00,0x62,0x7c]
-            cntlz  2, 3
-# CHECK-BE: cntlz. 2, 3                    # encoding: [0x7c,0x62,0x00,0x35]
-# CHECK-LE: cntlz. 2, 3                    # encoding: [0x35,0x00,0x62,0x7c]
-            cntlz.  2, 3
+#
+# The POWER variant of cntlzw
+# CHECK-BE: cntlzw 2, 3                     # encoding: [0x7c,0x62,0x00,0x34]
+# CHECK-LE: cntlzw 2, 3                     # encoding: [0x34,0x00,0x62,0x7c]
+            cntlz 2, 3
+# CHECK-BE: cntlzw. 2, 3                    # encoding: [0x7c,0x62,0x00,0x35]
+# CHECK-LE: cntlzw. 2, 3                    # encoding: [0x35,0x00,0x62,0x7c]
+            cntlz. 2, 3
             cmpb 7, 21, 4
 # CHECK-BE: cmpb 7, 21, 4                   # encoding: [0x7e,0xa7,0x23,0xf8]
 # CHECK-LE: cmpb 7, 21, 4                   # encoding: [0xf8,0x23,0xa7,0x7e]
 # FIXME:    popcntb 2, 3
 # CHECK-BE: popcntw 2, 3                    # encoding: [0x7c,0x62,0x02,0xf4]
 # CHECK-LE: popcntw 2, 3                    # encoding: [0xf4,0x02,0x62,0x7c]
             popcntw 2, 3
 # FIXME:    prtyd 2, 3