[clang] Fixed vec_pack_to_short_fp32 in Clang altivec.h (PR #129923)

[John Platts via cfe-commits]

https://github.com/johnplatts updated https://github.com/llvm/llvm-project/pull/129923

>From 0bfa20f7a2deaf61e444404f7418f4571a9d6de4 Mon Sep 17 00:00:00 2001
From: John Platts <john_platts at hotmail.com>
Date: Wed, 5 Mar 2025 13:11:15 -0600
Subject: [PATCH 1/3] Fixed vec_pack_to_short_fp32 in Clang altivec.h

---
 clang/lib/Headers/altivec.h | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/clang/lib/Headers/altivec.h b/clang/lib/Headers/altivec.h
index 8da65055012f1..45d557238e3d9 100644
--- a/clang/lib/Headers/altivec.h
+++ b/clang/lib/Headers/altivec.h
@@ -7529,13 +7529,9 @@ vec_pack(vector double __a, vector double __b) {
 #ifdef __POWER9_VECTOR__
 static __inline__ vector unsigned short __ATTRS_o_ai
 vec_pack_to_short_fp32(vector float __a, vector float __b) {
-  vector float __resa = __builtin_vsx_xvcvsphp(__a);
-  vector float __resb = __builtin_vsx_xvcvsphp(__b);
-#ifdef __LITTLE_ENDIAN__
-  return (vector unsigned short)vec_mergee(__resa, __resb);
-#else
-  return (vector unsigned short)vec_mergeo(__resa, __resb);
-#endif
+  vector unsigned int __resa = (vector unsigned int)__builtin_vsx_xvcvsphp(__a);
+  vector unsigned int __resb = (vector unsigned int)__builtin_vsx_xvcvsphp(__b);
+  return vec_pack(__resa, __resb);
 }
 
 #endif

>From 51c05790f7cd38e6db324dcd55b7491118b1c3e2 Mon Sep 17 00:00:00 2001
From: Lei Huang <lei at ca.ibm.com>
Date: Fri, 7 Mar 2025 13:44:52 -0500
Subject: [PATCH 2/3] add additional checks to test for vec_pack_to_short_fp32

---
 clang/test/CodeGen/PowerPC/builtins-ppc-p9vector.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/clang/test/CodeGen/PowerPC/builtins-ppc-p9vector.c b/clang/test/CodeGen/PowerPC/builtins-ppc-p9vector.c
index b55a522ed2608..68d32ee14c8fa 100644
--- a/clang/test/CodeGen/PowerPC/builtins-ppc-p9vector.c
+++ b/clang/test/CodeGen/PowerPC/builtins-ppc-p9vector.c
@@ -853,10 +853,16 @@ vector unsigned char test73(void) {
 vector unsigned short test74(void) {
 // CHECK-BE: @llvm.ppc.vsx.xvcvsphp(<4 x float>
 // CHECK-BE: @llvm.ppc.vsx.xvcvsphp(<4 x float>
-// CHECK-BE: @llvm.ppc.altivec.vperm
+// CHECK-BE: [[REG0:%[0-9]+]] = call <4 x i32> @llvm.ppc.altivec.vperm
+// CHECK-BE-NEXT: [[REG1:%[0-9]+]] = bitcast <4 x i32> [[REG0]] to <4 x float>
+// CHECK-BE-NEXT: [[REG2:%[0-9]+]] = bitcast <4 x float> [[REG1]] to <8 x i16>
+// CHECK-BE-NEXT: ret <8 x i16> [[REG2]]
 // CHECK: @llvm.ppc.vsx.xvcvsphp(<4 x float>
 // CHECK: @llvm.ppc.vsx.xvcvsphp(<4 x float>
-// CHECK: @llvm.ppc.altivec.vperm
+// CHECK: [[REG0:%[0-9]+]] = call <4 x i32> @llvm.ppc.altivec.vperm
+// CHECK-NEXT: [[REG1:%[0-9]+]] = bitcast <4 x i32> [[REG0]] to <4 x float>
+// CHECK-NEXT: [[REG2:%[0-9]+]] = bitcast <4 x float> [[REG1]] to <8 x i16>
+// CHECK-NEXT: ret <8 x i16> [[REG2]]
   return vec_pack_to_short_fp32(vfa, vfb);
 }
 vector unsigned int test75(void) {

>From 9aed4ea26d7dbe5fa786638eeabcbf7a8f0f51c0 Mon Sep 17 00:00:00 2001
From: John Platts <john_platts at hotmail.com>
Date: Fri, 7 Mar 2025 15:03:35 -0600
Subject: [PATCH 3/3] Updated test to reflect changes made to
 vec_pack_to_short_fp32

---
 clang/test/CodeGen/PowerPC/builtins-ppc-p9vector.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/clang/test/CodeGen/PowerPC/builtins-ppc-p9vector.c b/clang/test/CodeGen/PowerPC/builtins-ppc-p9vector.c
index 68d32ee14c8fa..824267b98564e 100644
--- a/clang/test/CodeGen/PowerPC/builtins-ppc-p9vector.c
+++ b/clang/test/CodeGen/PowerPC/builtins-ppc-p9vector.c
@@ -854,15 +854,13 @@ vector unsigned short test74(void) {
 // CHECK-BE: @llvm.ppc.vsx.xvcvsphp(<4 x float>
 // CHECK-BE: @llvm.ppc.vsx.xvcvsphp(<4 x float>
 // CHECK-BE: [[REG0:%[0-9]+]] = call <4 x i32> @llvm.ppc.altivec.vperm
-// CHECK-BE-NEXT: [[REG1:%[0-9]+]] = bitcast <4 x i32> [[REG0]] to <4 x float>
-// CHECK-BE-NEXT: [[REG2:%[0-9]+]] = bitcast <4 x float> [[REG1]] to <8 x i16>
-// CHECK-BE-NEXT: ret <8 x i16> [[REG2]]
+// CHECK-BE-NEXT: [[REG1:%[0-9]+]] = bitcast <4 x i32> [[REG0]] to <8 x i16>
+// CHECK-BE-NEXT: ret <8 x i16> [[REG1]]
 // CHECK: @llvm.ppc.vsx.xvcvsphp(<4 x float>
 // CHECK: @llvm.ppc.vsx.xvcvsphp(<4 x float>
 // CHECK: [[REG0:%[0-9]+]] = call <4 x i32> @llvm.ppc.altivec.vperm
-// CHECK-NEXT: [[REG1:%[0-9]+]] = bitcast <4 x i32> [[REG0]] to <4 x float>
-// CHECK-NEXT: [[REG2:%[0-9]+]] = bitcast <4 x float> [[REG1]] to <8 x i16>
-// CHECK-NEXT: ret <8 x i16> [[REG2]]
+// CHECK-NEXT: [[REG1:%[0-9]+]] = bitcast <4 x i32> [[REG0]] to <8 x i16>
+// CHECK-NEXT: ret <8 x i16> [[REG1]]
   return vec_pack_to_short_fp32(vfa, vfb);
 }
 vector unsigned int test75(void) {