[X86][Clang] Add constexpr support for AVX512 kshift intrinsics

[medhatiwari]

Add AVX512 kshiftli/kshiftri mask intrinsics to be used in constexpr.

Enables constexpr evaluation for:

• _kshiftli_mask8/16/32/64
• _kshiftri_mask8/16/32/64

Fixes #162056

[github-actions]

Thank you for submitting a Pull Request (PR) to the LLVM Project!

This PR will be automatically labeled and the relevant teams will be notified.

If you wish to, you can add reviewers by using the "Reviewers" section on this page.

If this is not working for you, it is probably because you do not have write permissions for the repository. In which case you can instead tag reviewers by name in a comment by using @ followed by their GitHub username.

If you have received no comments on your PR for a week, you can request a review by "ping"ing the PR by adding a comment “Ping”. The common courtesy "ping" rate is once a week. Please remember that you are asking for valuable time from other developers.

If you have further questions, they may be answered by the LLVM GitHub User Guide.

You can also ask questions in a comment on this PR, on the LLVM Discord or on the forums.

[llvmbot]

@llvm/pr-subscribers-clang

@llvm/pr-subscribers-backend-x86

Author: Medha Tiwari (medhatiwari)

Changes

Add AVX512 kshiftli/kshiftri mask intrinsics to be used in constexpr.

Enables constexpr evaluation for:

• _kshiftli_mask8/16/32/64
• _kshiftri_mask8/16/32/64

Fixes #162056

---

Full diff: https://github.com/llvm/llvm-project/pull/170480.diff

6 Files Affected:

• (modified) clang/include/clang/Basic/BuiltinsX86.td (+6-6)
• (modified) clang/lib/AST/ByteCode/InterpBuiltin.cpp (+22)
• (modified) clang/lib/AST/ExprConstant.cpp (+22)
• (modified) clang/test/CodeGen/X86/avx512bw-builtins.c (+17)
• (modified) clang/test/CodeGen/X86/avx512dq-builtins.c (+9)
• (modified) clang/test/CodeGen/X86/avx512f-builtins.c (+9)

diff --git a/clang/include/clang/Basic/BuiltinsX86.td b/clang/include/clang/Basic/BuiltinsX86.td
index b62928008dd2e..560f94ff2427e 100644
--- a/clang/include/clang/Basic/BuiltinsX86.td
+++ b/clang/include/clang/Basic/BuiltinsX86.td
@@ -3148,28 +3148,28 @@ let Features = "avx512bw", Attributes = [NoThrow, Const, Constexpr] in {
   def kxordi : X86Builtin<"unsigned long long int(unsigned long long int, unsigned long long int)">;
 }
 
-let Features = "avx512dq", Attributes = [NoThrow, Const] in {
+let Features = "avx512dq", Attributes = [NoThrow, Const, Constexpr] in {
   def kshiftliqi : X86Builtin<"unsigned char(unsigned char, _Constant unsigned int)">;
 }
 
-let Features = "avx512f", Attributes = [NoThrow, Const] in {
+let Features = "avx512f", Attributes = [NoThrow, Const, Constexpr] in {
   def kshiftlihi : X86Builtin<"unsigned short(unsigned short, _Constant unsigned int)">;
 }
 
-let Features = "avx512bw", Attributes = [NoThrow, Const] in {
+let Features = "avx512bw", Attributes = [NoThrow, Const, Constexpr] in {
   def kshiftlisi : X86Builtin<"unsigned int(unsigned int, _Constant unsigned int)">;
   def kshiftlidi : X86Builtin<"unsigned long long int(unsigned long long int, _Constant unsigned int)">;
 }
 
-let Features = "avx512dq", Attributes = [NoThrow, Const] in {
+let Features = "avx512dq", Attributes = [NoThrow, Const, Constexpr] in {
   def kshiftriqi : X86Builtin<"unsigned char(unsigned char, _Constant unsigned int)">;
 }
 
-let Features = "avx512f", Attributes = [NoThrow, Const] in {
+let Features = "avx512f", Attributes = [NoThrow, Const, Constexpr] in {
   def kshiftrihi : X86Builtin<"unsigned short(unsigned short, _Constant unsigned int)">;
 }
 
-let Features = "avx512bw", Attributes = [NoThrow, Const] in {
+let Features = "avx512bw", Attributes = [NoThrow, Const, Constexpr] in {
   def kshiftrisi : X86Builtin<"unsigned int(unsigned int, _Constant unsigned int)">;
   def kshiftridi : X86Builtin<"unsigned long long int(unsigned long long int, _Constant unsigned int)">;
 }
diff --git a/clang/lib/AST/ByteCode/InterpBuiltin.cpp b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
index 12e5e7d142aa4..eec6ff66bfc02 100644
--- a/clang/lib/AST/ByteCode/InterpBuiltin.cpp
+++ b/clang/lib/AST/ByteCode/InterpBuiltin.cpp
@@ -4255,6 +4255,28 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const CallExpr *Call,
           return APInt(sizeof(unsigned char) * 8, (A | B) == 0);
         });
 
+  case clang::X86::BI__builtin_ia32_kshiftliqi:
+  case clang::X86::BI__builtin_ia32_kshiftlihi:
+  case clang::X86::BI__builtin_ia32_kshiftlisi:
+  case clang::X86::BI__builtin_ia32_kshiftlidi:
+    return interp__builtin_elementwise_int_binop(
+        S, OpPC, Call, [](const APSInt &LHS, const APSInt &RHS) {
+          if (RHS.uge(LHS.getBitWidth()))
+            return APInt::getZero(LHS.getBitWidth());
+          return LHS.shl(RHS.getZExtValue());
+        });
+
+  case clang::X86::BI__builtin_ia32_kshiftriqi:
+  case clang::X86::BI__builtin_ia32_kshiftrihi:
+  case clang::X86::BI__builtin_ia32_kshiftrisi:
+  case clang::X86::BI__builtin_ia32_kshiftridi:
+    return interp__builtin_elementwise_int_binop(
+        S, OpPC, Call, [](const APSInt &LHS, const APSInt &RHS) {
+          if (RHS.uge(LHS.getBitWidth()))
+            return APInt::getZero(LHS.getBitWidth());
+          return LHS.lshr(RHS.getZExtValue());
+        });
+
   case clang::X86::BI__builtin_ia32_lzcnt_u16:
   case clang::X86::BI__builtin_ia32_lzcnt_u32:
   case clang::X86::BI__builtin_ia32_lzcnt_u64:
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index e707c10e5089c..5443e284beb9d 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -17054,6 +17054,28 @@ bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E,
     return Success(Val, E);
   }
 
+  case X86::BI__builtin_ia32_kshiftliqi:
+  case X86::BI__builtin_ia32_kshiftlihi:
+  case X86::BI__builtin_ia32_kshiftlisi:
+  case X86::BI__builtin_ia32_kshiftlidi: {
+    return HandleMaskBinOp([](const APSInt &LHS, const APSInt &RHS) {
+      if (RHS.uge(LHS.getBitWidth()))
+        return APSInt(APInt::getZero(LHS.getBitWidth()), LHS.isUnsigned());
+      return APSInt(LHS.shl(RHS.getZExtValue()), LHS.isUnsigned());
+    });
+  }
+
+  case X86::BI__builtin_ia32_kshiftriqi:
+  case X86::BI__builtin_ia32_kshiftrihi:
+  case X86::BI__builtin_ia32_kshiftrisi:
+  case X86::BI__builtin_ia32_kshiftridi: {
+    return HandleMaskBinOp([](const APSInt &LHS, const APSInt &RHS) {
+      if (RHS.uge(LHS.getBitWidth()))
+        return APSInt(APInt::getZero(LHS.getBitWidth()), LHS.isUnsigned());
+      return APSInt(LHS.lshr(RHS.getZExtValue()), LHS.isUnsigned());
+    });
+  }
+
   case clang::X86::BI__builtin_ia32_vec_ext_v4hi:
   case clang::X86::BI__builtin_ia32_vec_ext_v16qi:
   case clang::X86::BI__builtin_ia32_vec_ext_v8hi:
diff --git a/clang/test/CodeGen/X86/avx512bw-builtins.c b/clang/test/CodeGen/X86/avx512bw-builtins.c
index fd50ab97d2c42..f67e88d63577c 100644
--- a/clang/test/CodeGen/X86/avx512bw-builtins.c
+++ b/clang/test/CodeGen/X86/avx512bw-builtins.c
@@ -556,6 +556,23 @@ __mmask64 test_kshiftri_mask64(__m512i A, __m512i B, __m512i C, __m512i D) {
   return _mm512_mask_cmpneq_epu8_mask(_kshiftri_mask64(_mm512_cmpneq_epu8_mask(A, B), 32), C, D);
 }
 
+TEST_CONSTEXPR(_kshiftli_mask32(0x00000001, 1) == 0x00000002);
+TEST_CONSTEXPR(_kshiftli_mask32(0x00000001, 31) == 0x80000000);
+TEST_CONSTEXPR(_kshiftli_mask32(0x00000001, 32) == 0x00000000);
+TEST_CONSTEXPR(_kshiftli_mask32(0x0000FFFF, 8) == 0x00FFFF00);
+TEST_CONSTEXPR(_kshiftri_mask32(0x80000000, 1) == 0x40000000);
+TEST_CONSTEXPR(_kshiftri_mask32(0x80000000, 31) == 0x00000001);
+TEST_CONSTEXPR(_kshiftri_mask32(0x80000000, 32) == 0x00000000);
+TEST_CONSTEXPR(_kshiftri_mask32(0xFFFF0000, 8) == 0x00FFFF00);
+TEST_CONSTEXPR(_kshiftli_mask64(0x0000000000000001ULL, 1) == 0x0000000000000002ULL);
+TEST_CONSTEXPR(_kshiftli_mask64(0x0000000000000001ULL, 63) == 0x8000000000000000ULL);
+TEST_CONSTEXPR(_kshiftli_mask64(0x0000000000000001ULL, 64) == 0x0000000000000000ULL);
+TEST_CONSTEXPR(_kshiftli_mask64(0x00000000FFFFFFFFULL, 16) == 0x0000FFFFFFFF0000ULL);
+TEST_CONSTEXPR(_kshiftri_mask64(0x8000000000000000ULL, 1) == 0x4000000000000000ULL);
+TEST_CONSTEXPR(_kshiftri_mask64(0x8000000000000000ULL, 63) == 0x0000000000000001ULL);
+TEST_CONSTEXPR(_kshiftri_mask64(0x8000000000000000ULL, 64) == 0x0000000000000000ULL);
+TEST_CONSTEXPR(_kshiftri_mask64(0xFFFFFFFF00000000ULL, 16) == 0x0000FFFFFFFF0000ULL);
+
 unsigned int test_cvtmask32_u32(__m512i A, __m512i B) {
   // CHECK-LABEL: test_cvtmask32_u32
   return _cvtmask32_u32(_mm512_cmpneq_epu16_mask(A, B));
diff --git a/clang/test/CodeGen/X86/avx512dq-builtins.c b/clang/test/CodeGen/X86/avx512dq-builtins.c
index b8d9587af0394..839ae7ab5d5ea 100644
--- a/clang/test/CodeGen/X86/avx512dq-builtins.c
+++ b/clang/test/CodeGen/X86/avx512dq-builtins.c
@@ -372,6 +372,15 @@ __mmask8 test_kshiftri_mask8(__m512i A, __m512i B, __m512i C, __m512i D) {
   return _mm512_mask_cmpneq_epu64_mask(_kshiftri_mask8(_mm512_cmpneq_epu64_mask(A, B), 2), C, D);
 }
 
+TEST_CONSTEXPR(_kshiftli_mask8(0x01, 1) == 0x02);
+TEST_CONSTEXPR(_kshiftli_mask8(0x01, 7) == 0x80);
+TEST_CONSTEXPR(_kshiftli_mask8(0x01, 8) == 0x00);
+TEST_CONSTEXPR(_kshiftli_mask8(0x0F, 2) == 0x3C);
+TEST_CONSTEXPR(_kshiftri_mask8(0x80, 1) == 0x40);
+TEST_CONSTEXPR(_kshiftri_mask8(0x80, 7) == 0x01);
+TEST_CONSTEXPR(_kshiftri_mask8(0x80, 8) == 0x00);
+TEST_CONSTEXPR(_kshiftri_mask8(0xF0, 2) == 0x3C);
+
 unsigned int test_cvtmask8_u32(__m512i A, __m512i B) {
   // CHECK-LABEL: test_cvtmask8_u32
   // CHECK: zext i8 %{{.*}} to i32
diff --git a/clang/test/CodeGen/X86/avx512f-builtins.c b/clang/test/CodeGen/X86/avx512f-builtins.c
index 49e606e4ee1cb..8cb859e94556f 100644
--- a/clang/test/CodeGen/X86/avx512f-builtins.c
+++ b/clang/test/CodeGen/X86/avx512f-builtins.c
@@ -9581,6 +9581,15 @@ __mmask16 test_kshiftri_mask16(__m512i A, __m512i B, __m512i C, __m512i D) {
   return _mm512_mask_cmpneq_epu32_mask(_kshiftri_mask16(_mm512_cmpneq_epu32_mask(A, B), 1), C, D);
 }
 
+TEST_CONSTEXPR(_kshiftli_mask16(0x0001, 1) == 0x0002);
+TEST_CONSTEXPR(_kshiftli_mask16(0x0001, 15) == 0x8000);
+TEST_CONSTEXPR(_kshiftli_mask16(0x0001, 16) == 0x0000);
+TEST_CONSTEXPR(_kshiftli_mask16(0x00FF, 4) == 0x0FF0);
+TEST_CONSTEXPR(_kshiftri_mask16(0x8000, 1) == 0x4000);
+TEST_CONSTEXPR(_kshiftri_mask16(0x8000, 15) == 0x0001);
+TEST_CONSTEXPR(_kshiftri_mask16(0x8000, 16) == 0x0000);
+TEST_CONSTEXPR(_kshiftri_mask16(0xFF00, 4) == 0x0FF0);
+
 unsigned int test_cvtmask16_u32(__m512i A, __m512i B) {
   // CHECK-LABEL: test_cvtmask16_u32
   // CHECK: bitcast <16 x i1> %{{.*}} to i16

[RKSimon]

LGTM - cheers

[github-actions]

@medhatiwari Congratulations on having your first Pull Request (PR) merged into the LLVM Project!

Your changes will be combined with recent changes from other authors, then tested by our build bots. If there is a problem with a build, you may receive a report in an email or a comment on this PR.

Please check whether problems have been caused by your change specifically, as the builds can include changes from many authors. It is not uncommon for your change to be included in a build that fails due to someone else's changes, or infrastructure issues.

How to do this, and the rest of the post-merge process, is covered in detail here.

If your change does cause a problem, it may be reverted, or you can revert it yourself. This is a normal part of LLVM development. You can fix your changes and open a new PR to merge them again.

If you don't get any reports, no action is required from you. Your changes are working as expected, well done!