[llvm] 1d8f13a - [PowerPC] add a peephole to remove redundant swap instructions after vector splats on P8

[Ting Wang via llvm-commits]

Author: Ting Wang
Date: 2023-02-02T20:52:52-05:00
New Revision: 1d8f13ae4538fe49ecf3f59ddbd4e63b911107da

URL: https://github.com/llvm/llvm-project/commit/1d8f13ae4538fe49ecf3f59ddbd4e63b911107da
DIFF: https://github.com/llvm/llvm-project/commit/1d8f13ae4538fe49ecf3f59ddbd4e63b911107da.diff

LOG: [PowerPC] add a peephole to remove redundant swap instructions after vector splats on P8

Vector store on P8 little endian will have swap instruction added before
the store in PPCISelLowring. If the vector is generated by splat, the
swap instruction can be eliminated.

Reviewed By: shchenz

Differential Revision: https://reviews.llvm.org/D139691

Added: 
    

Modified: 
    llvm/lib/Target/PowerPC/PPCMIPeephole.cpp
    llvm/test/CodeGen/PowerPC/VSX-XForm-Scalars.ll
    llvm/test/CodeGen/PowerPC/aix-vsx-splatimm.ll
    llvm/test/CodeGen/PowerPC/canonical-merge-shuffles.ll
    llvm/test/CodeGen/PowerPC/load-and-splat.ll

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/PowerPC/PPCMIPeephole.cpp b/llvm/lib/Target/PowerPC/PPCMIPeephole.cpp
index 5b7761fb2d0df..af35669d0fab6 100644
--- a/llvm/lib/Target/PowerPC/PPCMIPeephole.cpp
+++ b/llvm/lib/Target/PowerPC/PPCMIPeephole.cpp
@@ -641,6 +641,18 @@ bool PPCMIPeephole::simplifyCode() {
           DefMI->getOperand(0).setReg(MI.getOperand(0).getReg());
           LLVM_DEBUG(dbgs() << "Removing redundant splat: ");
           LLVM_DEBUG(MI.dump());
+        } else if (Immed == 2 &&
+                   (DefOpc == PPC::VSPLTB || DefOpc == PPC::VSPLTH ||
+                    DefOpc == PPC::VSPLTW || DefOpc == PPC::XXSPLTW)) {
+          // Swap of various vector splats, convert to copy.
+          ToErase = &MI;
+          Simplified = true;
+          LLVM_DEBUG(dbgs() << "Optimizing swap(vsplt[b|h|w]|xxspltw) => "
+                               "copy(vsplt[b|h|w]|xxspltw): ");
+          LLVM_DEBUG(MI.dump());
+          BuildMI(MBB, &MI, MI.getDebugLoc(), TII->get(PPC::COPY),
+                  MI.getOperand(0).getReg())
+              .add(MI.getOperand(1));
         }
         break;
       }

diff  --git a/llvm/test/CodeGen/PowerPC/VSX-XForm-Scalars.ll b/llvm/test/CodeGen/PowerPC/VSX-XForm-Scalars.ll
index b5feacd1e92b2..6409023adfc53 100644
--- a/llvm/test/CodeGen/PowerPC/VSX-XForm-Scalars.ll
+++ b/llvm/test/CodeGen/PowerPC/VSX-XForm-Scalars.ll
@@ -14,7 +14,6 @@ define void @testExpandPostRAPseudo(ptr nocapture readonly %ptr) {
 ; CHECK-P8:    lfiwzx f0, 0, r3
 ; CHECK-P8:    ld r4, .LC0 at toc@l(r4)
 ; CHECK-P8:    xxspltw vs0, vs0, 1
-; CHECK-P8:    xxswapd vs0, vs0
 ; CHECK-P8;    stxvd2x vs0, 0, r4
 ; CHECK-P8:    lis r4, 1024
 ; CHECK-P8:    lfiwax f0, 0, r3

diff  --git a/llvm/test/CodeGen/PowerPC/aix-vsx-splatimm.ll b/llvm/test/CodeGen/PowerPC/aix-vsx-splatimm.ll
index 0ed463002b782..249bd34cabbb0 100644
--- a/llvm/test/CodeGen/PowerPC/aix-vsx-splatimm.ll
+++ b/llvm/test/CodeGen/PowerPC/aix-vsx-splatimm.ll
@@ -47,13 +47,11 @@ define void @test_aix_splatimm(i32 %arg, i32 %arg1, i32 %arg2) {
 ; CHECK-NEXT:    li 3, 0
 ; CHECK-NEXT:    mullw 4, 4, 5
 ; CHECK-NEXT:    vsplth 2, 2, 3
-; CHECK-NEXT:    xxswapd 0, 34
+; CHECK-NEXT:    stxvd2x 34, 0, 3
 ; CHECK-NEXT:    neg 4, 4
 ; CHECK-NEXT:    mtvsrd 35, 4
-; CHECK-NEXT:    stxvd2x 0, 0, 3
 ; CHECK-NEXT:    vsplth 3, 3, 3
-; CHECK-NEXT:    xxswapd 1, 35
-; CHECK-NEXT:    stxvd2x 1, 0, 3
+; CHECK-NEXT:    stxvd2x 35, 0, 3
 bb:
   br i1 undef, label %bb22, label %bb3
 

diff  --git a/llvm/test/CodeGen/PowerPC/canonical-merge-shuffles.ll b/llvm/test/CodeGen/PowerPC/canonical-merge-shuffles.ll
index b6fe31cf70808..f5881c37e0333 100644
--- a/llvm/test/CodeGen/PowerPC/canonical-merge-shuffles.ll
+++ b/llvm/test/CodeGen/PowerPC/canonical-merge-shuffles.ll
@@ -1196,8 +1196,7 @@ define dso_local void @testByteSplat() #0 {
 ; CHECK-P7-NEXT:    lvx v3, 0, r3
 ; CHECK-P7-NEXT:    vperm v2, v3, v3, v2
 ; CHECK-P7-NEXT:    vspltb v2, v2, 15
-; CHECK-P7-NEXT:    xxswapd vs0, v2
-; CHECK-P7-NEXT:    stxvd2x vs0, 0, r3
+; CHECK-P7-NEXT:    stxvd2x v2, 0, r3
 ; CHECK-P7-NEXT:    blr
 ;
 ; P8-AIX-LABEL: testByteSplat:

diff  --git a/llvm/test/CodeGen/PowerPC/load-and-splat.ll b/llvm/test/CodeGen/PowerPC/load-and-splat.ll
index bed9bc0a62987..3d31677714824 100644
--- a/llvm/test/CodeGen/PowerPC/load-and-splat.ll
+++ b/llvm/test/CodeGen/PowerPC/load-and-splat.ll
@@ -84,7 +84,6 @@ define dso_local void @test2(ptr nocapture %c, ptr nocapture readonly %a) local_
 ; P8-NEXT:    addi r4, r4, 12
 ; P8-NEXT:    lfiwzx f0, 0, r4
 ; P8-NEXT:    xxspltw vs0, vs0, 1
-; P8-NEXT:    xxswapd vs0, vs0
 ; P8-NEXT:    stxvd2x vs0, 0, r3
 ; P8-NEXT:    blr
 ;
@@ -141,7 +140,6 @@ define dso_local void @test3(ptr nocapture %c, ptr nocapture readonly %a) local_
 ; P8-NEXT:    addi r4, r4, 12
 ; P8-NEXT:    lfiwzx f0, 0, r4
 ; P8-NEXT:    xxspltw vs0, vs0, 1
-; P8-NEXT:    xxswapd vs0, vs0
 ; P8-NEXT:    stxvd2x vs0, 0, r3
 ; P8-NEXT:    blr
 ;