[Clang][X86] allow VPERMILPD/S imm intrinsics to be used in constexpr

[stomfaig]

adding cases for vpermilpd and vpermilps in InterpBultin.

Resolves #166529

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@llvm/pr-subscribers-clang

Author: None (stomfaig)

Changes

adding cases for vpermilpd and vpermilps in InterpBultin.

Resolves #166529

---

Full diff: https://github.com/llvm/llvm-project/pull/168044.diff

1 Files Affected:

• (modified) clang/lib/AST/ByteCode/InterpBuiltin.cpp (+30)

diff --git a/clang/lib/AST/ByteCode/InterpBuiltin.cpp b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
index cee3c1b8cf8f3..9ea66c6de7553 100644
--- a/clang/lib/AST/ByteCode/InterpBuiltin.cpp
+++ b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
@@ -4562,6 +4562,36 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const CallExpr *Call,
           unsigned Sel = (ShuffleMask >> (2 * LaneIdx)) & 0x3;
           return std::make_pair(0, static_cast<int>(LaneBase + Sel));
         });
+  
+  case X86::BI__builtin_ia32_vpermilpd:
+  case X86::BI__builtin_ia32_vpermilpd256:
+  case X86::BI__builtin_ia32_vpermilpd512:
+    return interp__builtin_ia32_shuffle_generic(S, OpPC, Call, [](unsigned DstIdx, unsigned Control) {
+      unsigned NumElemPerLane = 2;
+      unsigned BitsPerElem = 1;
+      unsigned MaskBits = 8;
+      unsigned IndexMask = 0x1;
+      unsigned Lane = DstIdx / NumElemPerLane;
+      unsigned LaneOffset = Lane * NumElemPerLane;
+      unsigned BitIndex = (DstIdx * BitsPerElem) % MaskBits;
+      unsigned Index = (Control >> BitIndex) & IndexMask;
+      return std::make_pair(0, static_cast<int>(LaneOffset + Index));
+    });
+  
+  case X86::BI__builtin_ia32_vpermilps:
+  case X86::BI__builtin_ia32_vpermilps256:
+  case X86::BI__builtin_ia32_vpermilps512:
+    return interp__builtin_ia32_shuffle_generic(S, OpPC, Call, [](unsigned DstIdx, unsigned Control) {
+      unsigned NumElemPerLane = 4;
+      unsigned BitsPerElem = 2;
+      unsigned MaskBits = 8;
+      unsigned IndexMask = 0x3;
+      unsigned Lane = DstIdx / NumElemPerLane;
+      unsigned LaneOffset = Lane * NumElemPerLane;
+      unsigned BitIndex = (DstIdx * BitsPerElem) % MaskBits;
+      unsigned Index = (Control >> BitIndex) & IndexMask;
+      return std::make_pair(0, static_cast<int>(LaneOffset + Index));
+    });
 
   case X86::BI__builtin_ia32_kandqi:
   case X86::BI__builtin_ia32_kandhi:

[tbaederr]

This is missing changes to ExprConstant.cpp and tests.

[RKSimon]

Still missing ExprConstant handling and test coverage

[RKSimon]

These should match the PSHUFD handling - we can just add permilps as additional cases to that

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[stomfaig]

Sorry for the oversight, I moved vpermilps under pshufd handling and added ExprConstant impl.

[RKSimon]

test cases - again, _mm_permute_ps etc. can be adapted from existing _mm_shuffle_epi32 sse2/avx2/mask/maskz TEST_CONSTEXPR tests, but _mm_permute_pd etc will need fresh tests

[RKSimon]

LGTM - cheers

[github-actions]

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