[PowerPC][AIX]Do not emit xxspltd mnemonic on AIX.

[sfertile]

Summary

A bug in the system assembler can assemble the xxspltd extended menemonic into the wrong instruction (extracting the wrong element).
Emit the full xxpermdi with all operands to work around the problem.

[jsji]

Can we try adding Predicates in InstAlias for xxspltd ?

[jsji]

I have added a Predicates in https://reviews.llvm.org/D94458 for a similar mne, maybe you can rebase this to use that.

[sfertile]

In D94419#2491599, @jsji wrote:

I have added a Predicates in https://reviews.llvm.org/D94458 for a similar mne, maybe you can rebase this to use that.

Will do.

[sfertile]

Rebased on trunk.

[jsji]

LGTM. Thanks!

llvm/lib/Target/PowerPC/PPCInstrVSX.td

 } // AddedComplexity = 400
 
 //---------------------------- Instruction aliases ---------------------------//
 def : InstAlias<"xvmovdp $XT, $XB",
                 (XVCPSGNDP vsrc:$XT, vsrc:$XB, vsrc:$XB)>;
 def : InstAlias<"xvmovsp $XT, $XB",
                 (XVCPSGNSP vsrc:$XT, vsrc:$XB, vsrc:$XB)>;
 
+// Certain versions of the AIX assembler may missassemble these mnemonics.
+let Predicates = [ModernAs] in {
   def : InstAlias<"xxspltd $XT, $XB, 0",
                   (XXPERMDI vsrc:$XT, vsrc:$XB, vsrc:$XB, 0)>;
   def : InstAlias<"xxspltd $XT, $XB, 1",
                   (XXPERMDI vsrc:$XT, vsrc:$XB, vsrc:$XB, 3)>;
+  def : InstAlias<"xxspltd $XT, $XB, 0",
+                  (XXPERMDIs vsrc:$XT, vsfrc:$XB, 0)>;
+  def : InstAlias<"xxspltd $XT, $XB, 1",
+                  (XXPERMDIs vsrc:$XT, vsfrc:$XB, 3)>;
+}
+
 def : InstAlias<"xxmrghd $XT, $XA, $XB",
                 (XXPERMDI vsrc:$XT, vsrc:$XA, vsrc:$XB, 0)>;
 def : InstAlias<"xxmrgld $XT, $XA, $XB",
                 (XXPERMDI vsrc:$XT, vsrc:$XA, vsrc:$XB, 3)>;
 def : InstAlias<"xxswapd $XT, $XB",
                 (XXPERMDI vsrc:$XT, vsrc:$XB, vsrc:$XB, 2)>;
-def : InstAlias<"xxspltd $XT, $XB, 0",
-                (XXPERMDIs vsrc:$XT, vsfrc:$XB, 0)>;
-def : InstAlias<"xxspltd $XT, $XB, 1",
-                (XXPERMDIs vsrc:$XT, vsfrc:$XB, 3)>;
 def : InstAlias<"xxswapd $XT, $XB",
                 (XXPERMDIs vsrc:$XT, vsfrc:$XB, 2)>;
 def : InstAlias<"mfvrd $rA, $XT",
                 (MFVRD g8rc:$rA, vrrc:$XT), 0>;
 def : InstAlias<"mffprd $rA, $src",
                 (MFVSRD g8rc:$rA, f8rc:$src)>;
 def : InstAlias<"mtvrd $XT, $rA",
                 (MTVRD vrrc:$XT, g8rc:$rA), 0>;

llvm/test/CodeGen/PowerPC/xxpermdi_mnemonics.s

+; RUN: llc -mtriple powerpc64-ibm-aix-xcoff -mcpu=pwr8 --vec-extabi < %s | FileCheck --check-prefixes=CHECK,OLD %s
+; RUN: llc -mtriple powerpc-ibm-aix-xcoff -mcpu=pwr8 --vec-extabi < %s | FileCheck --check-prefixes=CHECK,OLD %s
+
+; RUN: llc -mtriple powerpc64-unknown-linux-gnu -mcpu=pwr8 < %s | FileCheck --check-prefixes=CHECK,MODERN  %s
+; RUN: llc -mtriple powerpc64-ibm-aix-xcoff -mcpu=pwr8 -mattr=+modern-aix-as --vec-extabi < %s | FileCheck --check-prefixes=CHECK,MODERN %s
+; RUN: llc -mtriple powerpc-ibm-aix-xcoff -mcpu=pwr8 -mattr=+modern-aix-as --vec-extabi < %s | FileCheck --check-prefixes=CHECK,MODERN %s
+
+define <2 x double> @splat1(<2 x double> %A, <2 x double> %B) {
+entry:
+  %0 = shufflevector <2 x double> %B, <2 x double> undef, <2 x i32> <i32 0, i32 0>
+  ret <2 x double> %0
+}
+
+; CHECK-LABEL: splat1
+; OLD:    xxmrghd 34, 35, 35
+; MODERN: xxspltd 34, 35, 0
+
+define <2 x double> @splat2(<2 x double> %A, <2 x double> %B) {
+entry:
+  %0 = shufflevector <2 x double> %B, <2 x double> undef, <2 x i32> <i32 1, i32 1>
+  ret <2 x double> %0
+}
+
+; CHECK-LABEL: splat2
+; OLD:    xxmrgld 34, 35, 35
+; MODERN: xxspltd 34, 35, 1
+
+define <2 x double> @swap(<2 x double> %A, <2 x double> %B) {
+entry:
+  %0 = shufflevector <2 x double> %B, <2 x double> undef, <2 x i32> <i32 1, i32 0>
+  ret <2 x double> %0
+}
+
+; CHECK-LABEL: swap
+; CHECK: xxswapd 34, 35
+
+define <2 x double> @mergehi(<2 x double> %A, <2 x double> %B) {
+entry:
+  %0 = shufflevector <2 x double> %A, <2 x double> %B, <2 x i32> <i32 0, i32 2>
+  ret <2 x double> %0
+}
+
+; CHECK-LABEL: mergehi
+; CHECK: xxmrghd 34, 34, 35
+
+define <2 x double> @mergelo(<2 x double> %A, <2 x double> %B) {
+entry:
+  %0 = shufflevector <2 x double> %A, <2 x double> %B, <2 x i32> <i32 1, i32 3>
+  ret <2 x double> %0
+}
+
+; CHECK-LABEL: mergelo
+; CHECK: xxmrgld 34, 34, 35

llvm/test/MC/PowerPC/modern-aix-as.s

 # RUN: llvm-mc -triple powerpc64-unknown-unknown -mattr=+modern-aix-as --show-encoding %s | FileCheck -check-prefix=CHECK-BE %s
 # RUN: llvm-mc -triple powerpc64le-unknown-unknown -mattr=+modern-aix-as --show-encoding %s | FileCheck -check-prefix=CHECK-LE %s
 # RUN: llvm-mc -triple powerpc64le-unknown-unknown -mattr=-modern-aix-as --show-encoding %s | FileCheck -check-prefix=CHECK-LE %s
 # RUN: not llvm-mc -triple powerpc64le-unknown-unknown -mattr=+aix --show-encoding %s 2>&1 | FileCheck -check-prefix=CHECK-OLD %s
 ##TODO: Replace above with following when implement createXCOFFAsmParser
 # UN: llvm-mc -triple powerpc-aix-ibm-xcoff -mattr=+modern-aix-as --show-encoding %s 2>&1 | FileCheck -check-prefix=CHECK-BE %s
 # UN: not llvm-mc -triple powerpc-aix-ibm-xcoff --show-encoding %s 2>&1 | FileCheck -check-prefix=CHECK-OLD %s
 
 # CHECK-BE: mtudscr 2                       # encoding: [0x7c,0x43,0x03,0xa6]
 # CHECK-LE: mtudscr 2                       # encoding: [0xa6,0x03,0x43,0x7c]
 # CHECK-OLD: instruction use requires an option to be enabled
             mtudscr 2
 # CHECK-BE: mfudscr 2                       # encoding: [0x7c,0x43,0x02,0xa6]
 # CHECK-LE: mfudscr 2                       # encoding: [0xa6,0x02,0x43,0x7c]
+# CHECK-OLD: instruction use requires an option to be enabled
             mfudscr 2
+# CHECK-BE: xxspltd 2, 3, 0                 # encoding: [0xf0,0x43,0x18,0x50]
+# CHECK-LE: xxspltd 2, 3, 0                 # encoding: [0x50,0x18,0x43,0xf0]
+# CHECK-OLD: instruction use requires an option to be enabled
+            xxspltd 2, 3, 0
 
+# CHECK-BE: xxspltd 2, 3, 1                 # encoding: [0xf0,0x43,0x1b,0x50]
+# CHECK-LE: xxspltd 2, 3, 1                 # encoding: [0x50,0x1b,0x43,0xf0]
+# CHECK-OLD: instruction use requires an option to be enabled
+            xxspltd 2, 3, 1