[clang] [Clang][PowerPC] Add missing _mm_loadu_si64 to ppc_wrappers/emmintrin.h (PR #187315)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-backend-powerpc

Author: AutoJanitor (Scottcjn)

<details>
<summary>Changes</summary>

## Summary

Add the missing `_mm_loadu_si64` intrinsic to `clang/lib/Headers/ppc_wrappers/emmintrin.h`. This loads a 64-bit integer from unaligned memory into the lower 64 bits of `__m128i`, zeroing the upper bits.

GCC provides this intrinsic in its PPC SSE2 compatibility header but Clang doesn't, causing build failures for SSE2 code compiled on PowerPC via the compatibility layer (e.g., Skia).

The implementation delegates to `_mm_set_epi64`, matching the existing `_mm_loadl_epi64` pattern already in the file.

Fixes https://github.com/llvm/llvm-project/issues/91247

## Test plan

- Added call to `_mm_loadu_si64` in `ppc-emmintrin.c` test
- Added FileCheck pattern verifying the expected `_mm_set_epi64` call is emitted
- Verified on IBM POWER8 S824 (ppc64le) that the intrinsic compiles and produces correct VSX instructions

---
Full diff: https://github.com/llvm/llvm-project/pull/187315.diff


2 Files Affected:

- (modified) clang/lib/Headers/ppc_wrappers/emmintrin.h (+6) 
- (modified) clang/test/CodeGen/PowerPC/ppc-emmintrin.c (+4) 


``````````diff
diff --git a/clang/lib/Headers/ppc_wrappers/emmintrin.h b/clang/lib/Headers/ppc_wrappers/emmintrin.h
index fc18ab9d43b15..fbe5294988efd 100644
--- a/clang/lib/Headers/ppc_wrappers/emmintrin.h
+++ b/clang/lib/Headers/ppc_wrappers/emmintrin.h
@@ -762,6 +762,12 @@ extern __inline __m128i
   return (__m128i)(vec_vsx_ld(0, (signed int const *)__P));
 }
 
+extern __inline __m128i
+    __attribute__((__gnu_inline__, __always_inline__, __artificial__))
+    _mm_loadu_si64(void const *__P) {
+  return _mm_set_epi64((__m64)0LL, *(__m64 *)__P);
+}
+
 extern __inline __m128i
     __attribute__((__gnu_inline__, __always_inline__, __artificial__))
     _mm_loadl_epi64(__m128i_u const *__P) {
diff --git a/clang/test/CodeGen/PowerPC/ppc-emmintrin.c b/clang/test/CodeGen/PowerPC/ppc-emmintrin.c
index 88bf84eb81574..01053b937adb1 100644
--- a/clang/test/CodeGen/PowerPC/ppc-emmintrin.c
+++ b/clang/test/CodeGen/PowerPC/ppc-emmintrin.c
@@ -607,6 +607,7 @@ test_load() {
   resd = _mm_loadl_pd(md1, dp);
   resd = _mm_loadr_pd(dp);
   resd = _mm_loadu_pd(dp);
+  resi = _mm_loadu_si64(mip);
   resi = _mm_loadu_si128(mip);
 }
 
@@ -654,6 +655,9 @@ test_load() {
 // CHECK: %[[ADDR:[0-9a-zA-Z_.]+]] = load ptr, ptr %{{[0-9a-zA-Z_.]+}}, align 8
 // CHECK: call <2 x double> @vec_vsx_ld(int, double const*)(i32 noundef signext 0, ptr noundef %[[ADDR]])
 
+// CHECK-LABEL: define available_externally <2 x i64> @_mm_loadu_si64
+// CHECK: call <2 x i64> @_mm_set_epi64(i64 noundef 0, i64 noundef %{{[0-9a-zA-Z_.]+}})
+
 // CHECK-LABEL: define available_externally <2 x i64> @_mm_loadu_si128
 // CHECK: load ptr, ptr %{{[0-9a-zA-Z_.]+}}, align 8
 // CHECK: call <4 x i32> @vec_vsx_ld(int, int const*)(i32 noundef signext 0, ptr noundef %{{[0-9a-zA-Z_.]+}})

``````````

</details>


https://github.com/llvm/llvm-project/pull/187315