[PATCH] D95634: [PowerPC][Power10] Fix XXSPLI32DX not correctly exploiting specific cases

[Albion Fung via Phabricator via llvm-commits]

This revision was landed with ongoing or failed builds.
This revision was automatically updated to reflect the committed changes.
Conanap marked 4 inline comments as done.
Closed by commit rG2e470e03b49f: [PowerPC][Power10] Fix XXSPLI32DX not correctly exploiting specific cases (authored by Conanap).

Changed prior to commit:
  https://reviews.llvm.org/D95634?vs=319916&id=319937#toc

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D95634/new/

https://reviews.llvm.org/D95634

Files:
  llvm/lib/Target/PowerPC/PPCISelLowering.cpp
  llvm/test/CodeGen/PowerPC/p10-splatImm32.ll


Index: llvm/test/CodeGen/PowerPC/p10-splatImm32.ll
===================================================================
--- llvm/test/CodeGen/PowerPC/p10-splatImm32.ll
+++ llvm/test/CodeGen/PowerPC/p10-splatImm32.ll
@@ -101,23 +101,11 @@
   ret <8 x i16> <i16 291, i16 undef, i16 undef, i16 364, i16 undef, i16 1, i16 173, i16 undef>
 }
 
-define dso_local <16 x i8> @test_xxsplti32dx_10() {
-; CHECK-LABEL: test_xxsplti32dx_10:
-; CHECK:       # %bb.0: # %entry
-; CHECK-NEXT:    xxlxor vs34, vs34, vs34
-; CHECK-NEXT:    xxsplti32dx vs34, 0, 1207959552
-; CHECK-NEXT:    blr
-entry:
-  ret <16 x i8> <i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 72, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 72>
-}
-
-; FIXME: It appears that there is something wrong with the computation
-;        of the 64-bit constant to splat so we cannot emit xxsplti32dx for
-;        this test case for now.
 define dso_local <16 x i8> @constSplatBug() {
 ; CHECK-LABEL: constSplatBug:
 ; CHECK:       # %bb.0: # %entry
-; CHECK-NEXT:    plxv vs34, .LCPI10_0 at PCREL(0), 1
+; CHECK-NEXT:    xxlxor vs34, vs34, vs34
+; CHECK-NEXT:    xxsplti32dx vs34, 0, 1191182336
 ; CHECK-NEXT:    blr
 entry:
   ret <16 x i8> <i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 71, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 0, i8 71>
Index: llvm/lib/Target/PowerPC/PPCISelLowering.cpp
===================================================================
--- llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -8604,16 +8604,19 @@
 
   // If it is a splat of a double, check if we can shrink it to a 32 bit
   // non-denormal float which when converted back to double gives us the same
-  // double. This is to exploit the XXSPLTIDP instruction.+  // If we lose precision, we use XXSPLTI32DX.
+  // double. This is to exploit the XXSPLTIDP instruction.
+  // If we lose precision, we use XXSPLTI32DX.
   if (BVNIsConstantSplat && (SplatBitSize == 64) &&
       Subtarget.hasPrefixInstrs()) {
-    if (convertToNonDenormSingle(APSplatBits) &&
-        (Op->getValueType(0) == MVT::v2f64)) {
+    // Check the type first to short-circuit so we don't modify APSplatBits if
+    // this block isn't executed.
+    if ((Op->getValueType(0) == MVT::v2f64) &&
+        convertToNonDenormSingle(APSplatBits)) {
       SDValue SplatNode = DAG.getNode(
           PPCISD::XXSPLTI_SP_TO_DP, dl, MVT::v2f64,
           DAG.getTargetConstant(APSplatBits.getZExtValue(), dl, MVT::i32));
       return DAG.getBitcast(Op.getValueType(), SplatNode);
-    } else if (APSplatBits.getBitWidth() == 64) {
+    } else {
       // We may lose precision, so we have to use XXSPLTI32DX.
 
       uint32_t Hi =


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