release/19.x: [PowerPC] Fix assert exposed by PR 95931 in LowerBITCAST (#108062)

[llvmbot]

Backport 22067a8

Requested by: @syzaara

[llvmbot]

@amy-kwan What do you think about merging this PR to the release branch?

[llvmbot]

@llvm/pr-subscribers-backend-powerpc

Author: None (llvmbot)

Changes

Backport 22067a8

Requested by: @syzaara

---

Full diff: https://github.com/llvm/llvm-project/pull/108834.diff

2 Files Affected:

• (modified) llvm/lib/Target/PowerPC/PPCISelLowering.cpp (+5-4)
• (modified) llvm/test/CodeGen/PowerPC/f128-bitcast.ll (+22)

diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 21cf4d9eeac173..758de9d732fa7e 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -9338,12 +9338,13 @@ SDValue PPCTargetLowering::LowerBITCAST(SDValue Op, SelectionDAG &DAG) const {
   SDLoc dl(Op);
   SDValue Op0 = Op->getOperand(0);
 
+  if (!Subtarget.isPPC64() || (Op0.getOpcode() != ISD::BUILD_PAIR) ||
+      (Op.getValueType() != MVT::f128))
+    return SDValue();
+
   SDValue Lo = Op0.getOperand(0);
   SDValue Hi = Op0.getOperand(1);
-
-  if ((Op.getValueType() != MVT::f128) ||
-      (Op0.getOpcode() != ISD::BUILD_PAIR) || (Lo.getValueType() != MVT::i64) ||
-      (Hi.getValueType() != MVT::i64) || !Subtarget.isPPC64())
+  if ((Lo.getValueType() != MVT::i64) || (Hi.getValueType() != MVT::i64))
     return SDValue();
 
   if (!Subtarget.isLittleEndian())
diff --git a/llvm/test/CodeGen/PowerPC/f128-bitcast.ll b/llvm/test/CodeGen/PowerPC/f128-bitcast.ll
index ffbfbd0c64ff3f..55ba3cb1e05387 100644
--- a/llvm/test/CodeGen/PowerPC/f128-bitcast.ll
+++ b/llvm/test/CodeGen/PowerPC/f128-bitcast.ll
@@ -86,3 +86,25 @@ entry:
   ret i64 %1
 }
 
+define <4 x i32> @truncBitcast(i512 %a) {
+; CHECK-LABEL: truncBitcast:
+; CHECK:       # %bb.0: # %entry
+; CHECK-NEXT:    mtvsrdd v2, r4, r3
+; CHECK-NEXT:    blr
+;
+; CHECK-BE-LABEL: truncBitcast:
+; CHECK-BE:       # %bb.0: # %entry
+; CHECK-BE-NEXT:    mtvsrdd v2, r9, r10
+; CHECK-BE-NEXT:    blr
+;
+; CHECK-P8-LABEL: truncBitcast:
+; CHECK-P8:       # %bb.0: # %entry
+; CHECK-P8-NEXT:    mtfprd f0, r3
+; CHECK-P8-NEXT:    mtfprd f1, r4
+; CHECK-P8-NEXT:    xxmrghd v2, vs1, vs0
+; CHECK-P8-NEXT:    blr
+entry:
+  %0 = trunc i512 %a to i128
+  %1 = bitcast i128 %0 to <4 x i32>
+  ret <4 x i32> %1
+}

[stefanp-synopsys]

LGTM.

[syzaara]

@tru hi Tobias, can you please help to merge this PR? Thank you!

[github-actions]

@syzaara (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR.

[dyung]

@syzaara, not sure if you were notified, but the cherry-pick of this change to the release branch seems to be causing a test failure. Can you take a look?

• https://lab.llvm.org/buildbot/#/builders/102/builds/44
• https://lab.llvm.org/buildbot/#/builders/62/builds/37
• https://lab.llvm.org/buildbot/#/builders/31/builds/40
• https://lab.llvm.org/buildbot/#/builders/100/builds/40

[tru]

I am pretty sure this is not the PR that broke the tests since all the failures are related to LoongArch. I will try to revert some of the loongarch commits locally.