[llvm-branch-commits] [clang] [llvm] [ConstantTime] Native ct.select support for ARM64 (PR #166706)
Julius Alexandre via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Fri May 22 18:09:58 PDT 2026
https://github.com/wizardengineer updated https://github.com/llvm/llvm-project/pull/166706
>From b1122175ba40110a96dde4d75563206e17174d25 Mon Sep 17 00:00:00 2001
From: wizardengineer <juliuswoosebert at gmail.com>
Date: Wed, 5 Nov 2025 10:56:34 -0500
Subject: [PATCH 1/3] [ConstantTime][Clang] Add __builtin_ct_select for
constant-time selection
---
clang/docs/LanguageExtensions.rst | 44 ++
clang/include/clang/Basic/Builtins.td | 8 +
clang/lib/CodeGen/CGBuiltin.cpp | 13 +
clang/lib/Sema/SemaChecking.cpp | 64 ++
.../test/Sema/builtin-ct-select-edge-cases.c | 373 ++++++++++
clang/test/Sema/builtin-ct-select.c | 683 ++++++++++++++++++
6 files changed, 1185 insertions(+)
create mode 100644 clang/test/Sema/builtin-ct-select-edge-cases.c
create mode 100644 clang/test/Sema/builtin-ct-select.c
diff --git a/clang/docs/LanguageExtensions.rst b/clang/docs/LanguageExtensions.rst
index 03cb02deb5e7f..6f5cd5f95cdb0 100644
--- a/clang/docs/LanguageExtensions.rst
+++ b/clang/docs/LanguageExtensions.rst
@@ -7332,3 +7332,47 @@ Clang fails to reject some code that should be rejected. e.g.,
// own initializer rather than rejecting the code with an undeclared identifier
// diagnostic.
auto x = x;
+
+.. _langext-__builtin_ct_select:
+
+``__builtin_ct_select``
+-----------------------
+
+``__builtin_ct_select`` performs a constant-time conditional selection between
+two values. Unlike the ternary operator ``?:``, this builtin is designed to
+execute in constant time regardless of the condition value, making it suitable
+for cryptographic and security-sensitive code where timing side-channels must
+be avoided.
+
+**Syntax**:
+
+.. code-block:: c++
+
+ __builtin_ct_select(condition, true_value, false_value)
+
+**Examples**:
+
+.. code-block:: c++
+
+ // Select between two integers
+ int result = __builtin_ct_select(secret_bit, value_a, value_b);
+
+ // Select between two pointers
+ int *ptr = __builtin_ct_select(condition, ptr_a, ptr_b);
+
+ // Select between two floating-point values
+ double d = __builtin_ct_select(flag, 1.0, 2.0);
+
+**Description**:
+
+The first argument is an integer condition that is converted to a boolean
+(non-zero is true, zero is false). The second and third arguments must have
+the same scalar or vector type. The builtin returns the second argument if
+the condition is true, otherwise the third argument.
+
+The operation is guaranteed to be lowered to constant-time machine code that
+does not branch on the condition value, preventing timing-based side-channel
+attacks.
+
+Query for this feature with ``__has_builtin(__builtin_ct_select)``.
+
diff --git a/clang/include/clang/Basic/Builtins.td b/clang/include/clang/Basic/Builtins.td
index 40ec94ab75046..389754a37f7e3 100644
--- a/clang/include/clang/Basic/Builtins.td
+++ b/clang/include/clang/Basic/Builtins.td
@@ -5810,3 +5810,11 @@ def CountedByRef : Builtin {
let Attributes = [NoThrow, CustomTypeChecking];
let Prototype = "int(...)";
}
+
+// Constant-time select builtin
+def CtSelect : Builtin {
+ let Spellings = ["__builtin_ct_select"];
+ let Attributes = [NoThrow, Const, UnevaluatedArguments,
+ ConstIgnoringExceptions, CustomTypeChecking];
+ let Prototype = "void(...)";
+}
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index cac1628e68721..f69390b4ace57 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -6668,6 +6668,19 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
auto Str = CGM.GetAddrOfConstantCString(Name, "");
return RValue::get(Str.getPointer());
}
+ case Builtin::BI__builtin_ct_select: {
+ auto *Cond = EmitScalarExpr(E->getArg(0));
+ auto *A = EmitScalarExpr(E->getArg(1));
+ auto *B = EmitScalarExpr(E->getArg(2));
+
+ if (Cond->getType()->getIntegerBitWidth() != 1)
+ Cond = Builder.CreateICmpNE(
+ Cond, llvm::ConstantInt::get(Cond->getType(), 0), "cond.bool");
+
+ llvm::Function *Fn =
+ CGM.getIntrinsic(llvm::Intrinsic::ct_select, {A->getType()});
+ return RValue::get(Builder.CreateCall(Fn, {Cond, A, B}));
+ }
}
// If this is an alias for a lib function (e.g. __builtin_sin), emit
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index cc834bbee23c4..e5a15c84de8d3 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -3928,6 +3928,70 @@ Sema::CheckBuiltinFunctionCall(FunctionDecl *FDecl, unsigned BuiltinID,
if (BuiltinCountedByRef(TheCall))
return ExprError();
break;
+
+ case Builtin::BI__builtin_ct_select: {
+ if (TheCall->getNumArgs() != 3) {
+ // Simple argument count check without complex diagnostics
+ if (TheCall->getNumArgs() < 3) {
+ return Diag(TheCall->getEndLoc(),
+ diag::err_typecheck_call_too_few_args_at_least)
+ << 0 << 3 << TheCall->getNumArgs() << 0
+ << TheCall->getCallee()->getSourceRange();
+ } else {
+ return Diag(TheCall->getEndLoc(),
+ diag::err_typecheck_call_too_many_args)
+ << 0 << 3 << TheCall->getNumArgs() << 0
+ << TheCall->getCallee()->getSourceRange();
+ }
+ }
+ auto *Cond = TheCall->getArg(0);
+ auto *A = TheCall->getArg(1);
+ auto *B = TheCall->getArg(2);
+
+ QualType CondTy = Cond->getType();
+ if (!CondTy->isIntegerType()) {
+ return Diag(Cond->getBeginLoc(), diag::err_typecheck_cond_expect_scalar)
+ << CondTy << Cond->getSourceRange();
+ }
+
+ ExprResult ARes = DefaultFunctionArrayLvalueConversion(A);
+ ExprResult BRes = DefaultFunctionArrayLvalueConversion(B);
+ if (ARes.isInvalid() || BRes.isInvalid())
+ return ExprError();
+
+ A = ARes.get();
+ B = BRes.get();
+ TheCall->setArg(1, A);
+ TheCall->setArg(2, B);
+
+ QualType ATy = A->getType();
+ QualType BTy = B->getType();
+
+ // check for scalar or vector scalar type
+ if ((!ATy->isScalarType() && !ATy->isVectorType()) ||
+ (!BTy->isScalarType() && !BTy->isVectorType())) {
+ return Diag(A->getBeginLoc(),
+ diag::err_typecheck_cond_incompatible_operands)
+ << ATy << BTy << A->getSourceRange() << B->getSourceRange();
+ }
+
+ // Check if both operands have the same type or can be implicitly converted
+ if (!Context.hasSameType(ATy, BTy)) {
+ // For non-arithmetic types, they must be exactly the same
+ return Diag(A->getBeginLoc(),
+ diag::err_typecheck_cond_incompatible_operands)
+ << ATy << BTy << A->getSourceRange() << B->getSourceRange();
+ }
+
+ QualType ResultTy = ATy;
+ ExprResult CondRes = PerformContextuallyConvertToBool(Cond);
+ if (CondRes.isInvalid())
+ return ExprError();
+
+ TheCall->setArg(0, CondRes.get());
+ TheCall->setType(ResultTy);
+ return TheCall;
+ }
}
if (getLangOpts().HLSL && HLSL().CheckBuiltinFunctionCall(BuiltinID, TheCall))
diff --git a/clang/test/Sema/builtin-ct-select-edge-cases.c b/clang/test/Sema/builtin-ct-select-edge-cases.c
new file mode 100644
index 0000000000000..167b19bf20663
--- /dev/null
+++ b/clang/test/Sema/builtin-ct-select-edge-cases.c
@@ -0,0 +1,373 @@
+// RUN: %clang_cc1 -fsyntax-only -verify %s
+// RUN: %clang_cc1 -fsyntax-only -verify %s -fexperimental-new-constant-interpreter
+
+// Test with various condition expressions
+int test_conditional_expressions(int x, int y, int a, int b) {
+ // Logical expressions
+ int result1 = __builtin_ct_select(x && y, a, b);
+ int result2 = __builtin_ct_select(x || y, a, b);
+ int result3 = __builtin_ct_select(!x, a, b);
+
+ // Comparison expressions
+ int result4 = __builtin_ct_select(x == y, a, b);
+ int result5 = __builtin_ct_select(x != y, a, b);
+ int result6 = __builtin_ct_select(x < y, a, b);
+ int result7 = __builtin_ct_select(x > y, a, b);
+ int result8 = __builtin_ct_select(x <= y, a, b);
+ int result9 = __builtin_ct_select(x >= y, a, b);
+
+ // Bitwise expressions
+ int result10 = __builtin_ct_select(x & y, a, b);
+ int result11 = __builtin_ct_select(x | y, a, b);
+ int result12 = __builtin_ct_select(x ^ y, a, b);
+ int result13 = __builtin_ct_select(~x, a, b);
+
+ // Arithmetic expressions
+ int result14 = __builtin_ct_select(x + y, a, b);
+ int result15 = __builtin_ct_select(x - y, a, b);
+ int result16 = __builtin_ct_select(x * y, a, b);
+ int result17 = __builtin_ct_select(x / y, a, b);
+ int result18 = __builtin_ct_select(x % y, a, b);
+
+ return result1 + result2 + result3 + result4 + result5 + result6 + result7 + result8 + result9 + result10 + result11 + result12 + result13 + result14 + result15 + result16 + result17 + result18;
+}
+
+// Test with extreme values
+int test_extreme_values(int cond) {
+ // Maximum and minimum values
+ int max_int = __builtin_ct_select(cond, __INT_MAX__, -__INT_MAX__ - 1);
+
+ // Very large numbers
+ long long max_ll = __builtin_ct_select(cond, __LONG_LONG_MAX__, -__LONG_LONG_MAX__ - 1);
+
+ // Floating point extremes
+ float max_float = __builtin_ct_select(cond, __FLT_MAX__, -__FLT_MAX__);
+ double max_double = __builtin_ct_select(cond, __DBL_MAX__, -__DBL_MAX__);
+
+ return max_int;
+}
+
+// Test with zero and negative zero
+int test_zero_values(int cond) {
+ // Integer zeros
+ int zero_int = __builtin_ct_select(cond, 0, -0);
+
+ // Floating point zeros
+ float zero_float = __builtin_ct_select(cond, 0.0f, -0.0f);
+ double zero_double = __builtin_ct_select(cond, 0.0, -0.0);
+
+ return zero_int;
+}
+
+// Test with infinity and NaN
+int test_special_float_values(int cond) {
+ // Infinity
+ float inf_float = __builtin_ct_select(cond, __builtin_inff(), -__builtin_inff());
+ double inf_double = __builtin_ct_select(cond, __builtin_inf(), -__builtin_inf());
+
+ // NaN
+ float nan_float = __builtin_ct_select(cond, __builtin_nanf(""), __builtin_nanf(""));
+ double nan_double = __builtin_ct_select(cond, __builtin_nan(""), __builtin_nan(""));
+
+ return 0;
+}
+
+// Test with complex pointer scenarios
+int test_pointer_edge_cases(int cond) {
+ int arr[10];
+ int *ptr1 = arr;
+ int *ptr2 = arr + 5;
+
+ // Array pointers
+ int *result1 = __builtin_ct_select(cond, ptr1, ptr2);
+
+ // Pointer arithmetic
+ int *result2 = __builtin_ct_select(cond, arr + 1, arr + 2);
+
+ // NULL vs non-NULL
+ int *result3 = __builtin_ct_select(cond, ptr1, (int*)0);
+
+ // Different pointer types (should fail)
+ float *fptr = (float*)0;
+ int *result4 = __builtin_ct_select(cond, ptr1, fptr); // expected-error {{incompatible operand types ('int *' and 'float *')}}
+
+ return *result1;
+}
+
+// Test with function pointers
+int func1(int x) { return x; }
+int func2(int x) { return x * 2; }
+float func3(float x) { return x; }
+
+int test_function_pointers(int cond, int x) {
+ // Same signature function pointer
+ int (*fptr)(int) = __builtin_ct_select(cond, &func1, &func2);
+
+ // Different signature function pointers (should fail)
+ int (*bad_fptr)(int) = __builtin_ct_select(cond, &func1, &func3); // expected-error {{incompatible operand types ('int (*)(int)' and 'float (*)(float)')}}
+
+ return fptr(x);
+}
+
+// Test with void pointers
+void *test_void_pointers(int cond, void *a, void *b) {
+ return __builtin_ct_select(cond, a, b);
+}
+
+// Test with const/volatile qualifiers
+int test_qualifiers(int cond) {
+ const int ca = 10;
+ const int cb = 20;
+ volatile int va = 30;
+ volatile int vb = 40;
+ const volatile int cva = 50;
+ const volatile int cvb = 60;
+
+ // const to const
+ const int result1 = __builtin_ct_select(cond, ca, cb);
+
+ // volatile to volatile
+ volatile int result2 = __builtin_ct_select(cond, va, vb);
+
+ // const volatile to const volatile
+ const volatile int result3 = __builtin_ct_select(cond, cva, cvb);
+
+ return result1 + result2 + result3;
+}
+
+// Test with arrays (should fail as they're not arithmetic or pointer)
+int test_arrays(int cond) {
+ int arr1[5] = {1, 2, 3, 4, 5};
+ int arr2[5] = {6, 7, 8, 9, 10};
+
+ // This should fail??
+ int *result = __builtin_ct_select(cond, arr1, arr2);
+
+ return result[0];
+}
+
+// Test with structures (should fail)
+struct Point {
+ int x, y;
+};
+
+struct Point test_structs(int cond) {
+ struct Point p1 = {1, 2};
+ struct Point p2 = {3, 4};
+
+ return __builtin_ct_select(cond, p1, p2); // expected-error {{incompatible operand types ('struct Point' and 'struct Point')}}
+}
+
+// Test with unions (should fail)
+union Data {
+ int i;
+ float f;
+};
+
+union Data test_unions(int cond) {
+ union Data d1 = {.i = 10};
+ union Data d2 = {.i = 20};
+
+ return __builtin_ct_select(cond, d1, d2); // expected-error {{incompatible operand types ('union Data' and 'union Data')}}
+}
+
+// Test with bit fields (should work as they're integers)
+struct BitField {
+ int a : 4;
+ int b : 4;
+};
+
+int test_bit_fields(int cond) {
+ struct BitField bf1 = {1, 2};
+ struct BitField bf2 = {3, 4};
+
+ // Individual bit fields should work
+ int result1 = __builtin_ct_select(cond, bf1.a, bf2.a);
+ int result2 = __builtin_ct_select(cond, bf1.b, bf2.b);
+
+ return result1 + result2;
+}
+
+// Test with designated initializers
+int test_designated_init(int cond) {
+ int arr1[3] = {[0] = 1, [1] = 2, [2] = 3};
+ int arr2[3] = {[0] = 4, [1] = 5, [2] = 6};
+
+ // Access specific elements
+ int result1 = __builtin_ct_select(cond, arr1[0], arr2[0]);
+ int result2 = __builtin_ct_select(cond, arr1[1], arr2[1]);
+
+ return result1 + result2;
+}
+
+// Test with complex expressions in arguments
+int complex_expr(int x) { return x * x; }
+
+int test_complex_arguments(int cond, int x, int y) {
+ // Function calls as arguments
+ int result1 = __builtin_ct_select(cond, complex_expr(x), complex_expr(y));
+
+ // Ternary operator as arguments
+ int result2 = __builtin_ct_select(cond, x > 0 ? x : -x, y > 0 ? y : -y);
+
+ // Compound literals
+ int result3 = __builtin_ct_select(cond, (int){x}, (int){y});
+
+ return result1 + result2 + result3;
+}
+
+// Test with preprocessor macros
+#define MACRO_A 42
+#define MACRO_B 24
+#define MACRO_COND(x) (x > 0)
+
+int test_macros(int x) {
+ int result1 = __builtin_ct_select(MACRO_COND(x), MACRO_A, MACRO_B);
+
+ // Nested macros
+ #define NESTED_SELECT(c, a, b) __builtin_ct_select(c, a, b)
+ int result2 = NESTED_SELECT(x, 10, 20);
+
+ return result1 + result2;
+}
+
+// Test with string literals (should fail)
+const char *test_strings(int cond) {
+ return __builtin_ct_select(cond, "hello", "world");
+}
+
+// Test with variable length arrays (VLA)
+int test_vla(int cond, int n) {
+ int vla1[n];
+ int vla2[n];
+
+ // Individual elements should work
+ vla1[0] = 1;
+ vla2[0] = 2;
+ int result = __builtin_ct_select(cond, vla1[0], vla2[0]);
+
+ return result;
+}
+
+// Test with typedef
+typedef int MyInt;
+typedef float MyFloat;
+
+MyInt test_typedef(int cond, MyInt a, MyInt b) {
+ return __builtin_ct_select(cond, a, b);
+}
+
+// Test with different typedef types (should fail)
+MyInt test_different_typedef(int cond, MyInt a, MyFloat b) {
+ return __builtin_ct_select(cond, a, b); // expected-error {{incompatible operand types ('MyInt' (aka 'int') and 'MyFloat' (aka 'float'))}}
+}
+
+// Test with side effects (should be evaluated)
+int side_effect_counter = 0;
+int side_effect_func(int x) {
+ side_effect_counter++;
+ return x;
+}
+
+int test_side_effects(int cond) {
+ // Both arguments should be evaluated
+ int result = __builtin_ct_select(cond, side_effect_func(10), side_effect_func(20));
+ return result;
+}
+
+// Test with goto labels (context where expressions are used)
+int test_goto_context(int cond, int a, int b) {
+ int result = __builtin_ct_select(cond, a, b);
+
+ if (result > 0) {
+ goto positive;
+ } else {
+ goto negative;
+ }
+
+positive:
+ return result;
+
+negative:
+ return -result;
+}
+
+// Test with switch statements
+int test_switch_context(int cond, int a, int b) {
+ int result = __builtin_ct_select(cond, a, b);
+
+ switch (result) {
+ case 0:
+ return 0;
+ case 1:
+ return 1;
+ default:
+ return -1;
+ }
+}
+
+// Test with loops
+int test_loop_context(int cond, int a, int b) {
+ int result = __builtin_ct_select(cond, a, b);
+ int sum = 0;
+
+ for (int i = 0; i < result; i++) {
+ sum += i;
+ }
+
+ return sum;
+}
+
+// Test with recursive functions
+int factorial(int n) {
+ if (n <= 1) return 1;
+ return n * factorial(n - 1);
+}
+
+int test_recursive(int cond, int n) {
+ int result = __builtin_ct_select(cond, n, n + 1);
+ return factorial(result);
+}
+
+// Test with inline functions
+static inline int inline_func(int x) {
+ return x * 2;
+}
+
+int test_inline(int cond, int a, int b) {
+ return __builtin_ct_select(cond, inline_func(a), inline_func(b));
+}
+
+// Test with static variables
+int test_static_vars(int cond) {
+ static int static_a = 10;
+ static int static_b = 20;
+
+ return __builtin_ct_select(cond, static_a, static_b);
+}
+
+// Test with extern variables
+extern int extern_a;
+extern int extern_b;
+
+int test_extern_vars(int cond) {
+ return __builtin_ct_select(cond, extern_a, extern_b);
+}
+
+// Test with register variables
+int test_register_vars(int cond) {
+ register int reg_a = 30;
+ register int reg_b = 40;
+
+ return __builtin_ct_select(cond, reg_a, reg_b);
+}
+
+// Test with thread-local variables (C11)
+#if __STDC_VERSION__ >= 201112L
+_Thread_local int tls_a = 50;
+_Thread_local int tls_b = 60;
+
+int test_tls_vars(int cond) {
+ return __builtin_ct_select(cond, tls_a, tls_b);
+}
+#endif
diff --git a/clang/test/Sema/builtin-ct-select.c b/clang/test/Sema/builtin-ct-select.c
new file mode 100644
index 0000000000000..7f2d9291299d6
--- /dev/null
+++ b/clang/test/Sema/builtin-ct-select.c
@@ -0,0 +1,683 @@
+// RUN: %clang_cc1 -emit-llvm -o - %s | FileCheck %s
+
+// Test integer types
+int test_int(int cond, int a, int b) {
+ // CHECK-LABEL: define {{.*}} @test_int
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: ret i32 [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+long long test_long(int cond, long long a, long long b) {
+ // CHECK-LABEL: define {{.*}} @test_long
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call i64 @llvm.ct.select.i64(i1 [[COND]], i64 %{{.*}}, i64 %{{.*}})
+ // CHECK: ret i64 [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+short test_short(int cond, short a, short b) {
+ // CHECK-LABEL: define {{.*}} @test_short
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call i16 @llvm.ct.select.i16(i1 [[COND]], i16 %{{.*}}, i16 %{{.*}})
+ // CHECK: ret i16 [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+unsigned char test_uchar(int cond, unsigned char a, unsigned char b) {
+ // CHECK-LABEL: define {{.*}} @test_uchar
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call i8 @llvm.ct.select.i8(i1 [[COND]], i8 %{{.*}}, i8 %{{.*}})
+ // CHECK: ret i8 [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+long long test_longlong(int cond, long long a, long long b) {
+ // CHECK-LABEL: define {{.*}} @test_longlong
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call i64 @llvm.ct.select.i64(i1 [[COND]], i64 %{{.*}}, i64 %{{.*}})
+ // CHECK: ret i64 [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+// Test floating point types
+float test_float(int cond, float a, float b) {
+ // CHECK-LABEL: define {{.*}} @test_float
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call float @llvm.ct.select.f32(i1 [[COND]], float %{{.*}}, float %{{.*}})
+ // CHECK: ret float [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+double test_double(int cond, double a, double b) {
+ // CHECK-LABEL: define {{.*}} @test_double
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call double @llvm.ct.select.f64(i1 [[COND]], double %{{.*}}, double %{{.*}})
+ // CHECK: ret double [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+// Test pointer types
+int *test_pointer(int cond, int *a, int *b) {
+ // CHECK-LABEL: define {{.*}} @test_pointer
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call ptr @llvm.ct.select.p0(i1 [[COND]], ptr %{{.*}}, ptr %{{.*}})
+ // CHECK: ret ptr [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+// Test with different condition types
+int test_char_cond(char cond, int a, int b) {
+ // CHECK-LABEL: define {{.*}} @test_char_cond
+ // CHECK: [[COND:%.*]] = icmp ne i8 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: ret i32 [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+int test_long_cond(long long cond, int a, int b) {
+ // CHECK-LABEL: define {{.*}} @test_long_cond
+ // CHECK: [[COND:%.*]] = icmp ne i64 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: ret i32 [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+// Test with boolean condition
+int test_bool_cond(_Bool cond, int a, int b) {
+ // CHECK-LABEL: define {{.*}} @test_bool_cond
+ // CHECK: [[COND:%.*]] = icmp ne i8 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: ret i32 [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+// Test with constants
+int test_constant_cond(void) {
+ // CHECK-LABEL: define {{.*}} @test_constant_cond
+ // CHECK: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 true, i32 42, i32 24)
+ // CHECK: ret i32 [[RESULT]]
+ return __builtin_ct_select(1, 42, 24);
+}
+
+int test_zero_cond(void) {
+ // CHECK-LABEL: define {{.*}} @test_zero_cond
+ // CHECK: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 false, i32 42, i32 24)
+ // CHECK: ret i32 [[RESULT]]
+ return __builtin_ct_select(0, 42, 24);
+}
+
+// Test type promotion
+int test_promotion(int cond, short a, short b) {
+ // CHECK-LABEL: define {{.*}} @test_promotion
+ // CHECK-DAG: [[A_EXT:%.*]] = sext i16 %{{.*}} to i32
+ // CHECK-DAG: [[B_EXT:%.*]] = sext i16 %{{.*}} to i32
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND]], i32 [[A_EXT]], i32 [[B_EXT]])
+ // CHECK: ret i32 [[RESULT]]
+ return __builtin_ct_select(cond, (int)a, (int)b);
+}
+
+// Test mixed signedness
+unsigned int test_mixed_signedness(int cond, int a, unsigned int b) {
+ // CHECK-LABEL: define {{.*}} @test_mixed_signedness
+ // CHECK-DAG: [[A_EXT:%.*]] = sext i32 %{{.*}} to i64
+ // CHECK-DAG: [[B_EXT:%.*]] = zext i32 %{{.*}} to i64
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[RESULT:%.*]] = call i64 @llvm.ct.select.i64(i1 [[COND]], i64 [[A_EXT]], i64 [[B_EXT]])
+ // CHECK: [[RESULT_TRUNC:%.*]] = trunc i64 [[RESULT]] to i32
+ // CHECK: ret i32 [[RESULT_TRUNC]]
+ return __builtin_ct_select(cond, (long long)a, (long long)b);
+}
+
+// Test complex expression
+int test_complex_expr_alt(int x, int y) {
+ // CHECK-LABEL: define {{.*}} @test_complex_expr_alt
+ // CHECK-DAG: [[CMP:%.*]] = icmp sgt i32 %{{.*}}, 0
+ // CHECK-DAG: [[ADD:%.*]] = add nsw i32 %{{.*}}, %{{.*}}
+ // CHECK-DAG: [[SUB:%.*]] = sub nsw i32 %{{.*}}, %{{.*}}
+ // Separate the final sequence to ensure proper ordering
+ // CHECK-NEXT: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[CMP]], i32 [[ADD]], i32 [[SUB]])
+ // CHECK-NEXT: ret i32 [[RESULT]]
+ return __builtin_ct_select(x > 0, x + y, x - y);
+}
+
+// Test nested calls
+int test_nested_structured(int cond1, int cond2, int a, int b, int c) {
+ // CHECK-LABEL: define {{.*}} @test_nested_structured
+ // Phase 1: Conditions (order doesn't matter)
+ // CHECK-DAG: [[COND1:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[COND2:%.*]] = icmp ne i32 %{{.*}}, 0
+
+ // Phase 2: Inner select (must happen before outer)
+ // CHECK: [[INNER:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND2]], i32 %{{.*}}, i32 %{{.*}})
+
+ // Phase 3: Outer select (must use inner result)
+ // CHECK: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND1]], i32 [[INNER]], i32 %{{.*}})
+ // CHECK: ret i32 [[RESULT]]
+ return __builtin_ct_select(cond1, __builtin_ct_select(cond2, a, b), c);
+}
+
+// Test with function calls
+int helper(int x) { return x * 2; }
+int test_function_calls(int cond, int x, int y) {
+ // CHECK-LABEL: define {{.*}} @test_function_calls
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[CALL1:%.*]] = call i32 @helper(i32 noundef %{{.*}})
+ // CHECK-DAG: [[CALL2:%.*]] = call i32 @helper(i32 noundef %{{.*}})
+ // CHECK-DAG: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND]], i32 [[CALL1]], i32 [[CALL2]])
+ // CHECK: ret i32 [[RESULT]]
+ return __builtin_ct_select(cond, helper(x), helper(y));
+}
+
+// Test using ct_select as condition for another ct_select
+int test_intrinsic_condition(int cond1, int cond2, int a, int b, int c, int d) {
+ // CHECK-LABEL: define {{.*}} @test_intrinsic_condition
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[INNER_COND:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK-DAG: [[FINAL_COND:%.*]] = icmp ne i32 [[INNER_COND]], 0
+ // CHECK-DAG: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[FINAL_COND]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: ret i32 [[RESULT]]
+ return __builtin_ct_select(__builtin_ct_select(cond1, cond2, a), b, c);
+}
+
+// Test using comparison result of ct_select as condition
+int test_comparison_condition(int cond, int a, int b, int c, int d) {
+ // CHECK-LABEL: define {{.*}} @test_comparison_condition
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[FIRST_SELECT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: [[CMP:%.*]] = icmp sgt i32 [[FIRST_SELECT]], %{{.*}}
+ // CHECK: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[CMP]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: ret i32 [[RESULT]]
+ return __builtin_ct_select(__builtin_ct_select(cond, a, b) > c, d, a);
+}
+
+// Test using ct_select result in arithmetic as condition
+int test_arithmetic_condition(int cond, int a, int b, int c, int d) {
+ // CHECK-LABEL: define {{.*}} @test_arithmetic_condition
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[FIRST_SELECT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: [[ADD:%.*]] = add nsw i32 [[FIRST_SELECT]], %{{.*}}
+ // CHECK: [[FINAL_COND:%.*]] = icmp ne i32 [[ADD]], 0
+ // CHECK: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[FINAL_COND]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: ret i32 [[RESULT]]
+ return __builtin_ct_select(__builtin_ct_select(cond, a, b) + c, d, a);
+}
+
+// Test chained ct_select as conditions
+int test_chained_conditions(int cond1, int cond2, int cond3, int a, int b, int c, int d, int e) {
+ // CHECK-LABEL: define {{.*}} @test_chained_conditions
+ // CHECK: [[COND1:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[FIRST:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND1]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK-DAG: [[COND2:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[SECOND:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND2]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK-DAG: [[FINAL_COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[FINAL_COND]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: ret i32 [[RESULT]]
+ int first_select = __builtin_ct_select(cond1, a, b);
+ int second_select = __builtin_ct_select(cond2, first_select, c);
+ return __builtin_ct_select(second_select, d, e);
+}
+
+// Test using ct_select with pointer condition
+//int test_pointer_condition(int *ptr1, int *ptr2, int a, int b, int c) {
+ // NO-CHECK-LABEL: define {{.*}} @test_pointer_condition
+ // NO-CHECK: [[PTR_COND:%.*]] = icmp ne ptr %{{.*}}, null
+ // NO-CHECK: [[PTR_SELECT:%.*]] = call ptr @llvm.ct.select.p0(i1 [[PTR_COND]], ptr %{{.*}}, ptr %{{.*}})
+ // NO-CHECK: [[FINAL_COND:%.*]] = icmp ne ptr [[PTR_SELECT]], null
+ // NO-CHECK: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[FINAL_COND]], i32 %{{.*}}, i32 %{{.*}})
+ // NO-CHECK: ret i32 [[RESULT]]
+// return __builtin_ct_select(__builtin_ct_select(ptr1, ptr1, ptr2), a, b);
+//}
+
+
+// Test using ct_select result in logical operations as condition
+int test_logical_condition(int cond1, int cond2, int a, int b, int c, int d) {
+ // CHECK-LABEL: define {{.*}} @test_logical_condition
+ // CHECK-DAG: [[COND1:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[COND2:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[FIRST_SELECT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND1]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK-DAG: [[SELECT_BOOL:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 %{{.*}}, i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: ret i32 [[RESULT]]
+ return __builtin_ct_select(__builtin_ct_select(cond1, a, b) && cond2, c, d);
+}
+
+// Test multiple levels of ct_select as conditions
+int test_deep_condition_nesting(int cond1, int cond2, int cond3, int a, int b, int c, int d, int e, int f) {
+ // CHECK-LABEL: define {{.*}} @test_deep_condition_nesting
+ // CHECK-DAG: [[COND1:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[COND2:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[INNER1:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND2]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK-DAG: [[INNER1_COND:%.*]] = icmp ne i32 [[INNER1]], 0
+ // CHECK-DAG: [[INNER2:%.*]] = call i32 @llvm.ct.select.i32(i1 [[INNER1_COND]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK-DAG: [[OUTER:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND1]], i32 [[INNER2]], i32 %{{.*}})
+ // CHECK-DAG: [[FINAL_COND:%.*]] = icmp ne i32 [[OUTER]], 0
+ // CHECK-DAG: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[FINAL_COND]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: ret i32 [[RESULT]]
+ return __builtin_ct_select(__builtin_ct_select(cond1, __builtin_ct_select(__builtin_ct_select(cond2, a, b), c, d), e), f, a);
+}
+
+// Test ct_select with complex condition expressions
+int test_complex_condition_expr(int x, int y, int z, int a, int b) {
+ // CHECK-LABEL: define {{.*}} @test_complex_condition_expr
+ // CHECK: [[CMP1:%.*]] = icmp sgt i32 %{{.*}}, %{{.*}}
+ // CHECK: [[SELECT1:%.*]] = call i32 @llvm.ct.select.i32(i1 [[CMP1]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: [[CMP2:%.*]] = icmp slt i32 [[SELECT1]], %{{.*}}
+ // CHECK: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[CMP2]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: ret i32 [[RESULT]]
+ return __builtin_ct_select(__builtin_ct_select(x > y, x, y) < z, a, b);
+}
+
+// Test vector types - 128-bit vectors
+typedef int __attribute__((vector_size(16))) int4;
+typedef float __attribute__((vector_size(16))) float4;
+typedef short __attribute__((vector_size(16))) short8;
+typedef char __attribute__((vector_size(16))) char16;
+
+int4 test_vector_int4(int cond, int4 a, int4 b) {
+ // CHECK-LABEL: define {{.*}} @test_vector_int4
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call <4 x i32> @llvm.ct.select.v4i32(i1 [[COND]], <4 x i32> %{{.*}}, <4 x i32> %{{.*}})
+ // CHECK: ret <4 x i32> [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+float4 test_vector_float4(int cond, float4 a, float4 b) {
+ // CHECK-LABEL: define {{.*}} @test_vector_float4
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call <4 x float> @llvm.ct.select.v4f32(i1 [[COND]], <4 x float> %{{.*}}, <4 x float> %{{.*}})
+ // CHECK: ret <4 x float> [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+short8 test_vector_short8(int cond, short8 a, short8 b) {
+ // CHECK-LABEL: define {{.*}} @test_vector_short8
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call <8 x i16> @llvm.ct.select.v8i16(i1 [[COND]], <8 x i16> %{{.*}}, <8 x i16> %{{.*}})
+ // CHECK: ret <8 x i16> [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+char16 test_vector_char16(int cond, char16 a, char16 b) {
+ // CHECK-LABEL: define {{.*}} @test_vector_char16
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call <16 x i8> @llvm.ct.select.v16i8(i1 [[COND]], <16 x i8> %{{.*}}, <16 x i8> %{{.*}})
+ // CHECK: ret <16 x i8> [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+// Test 256-bit vectors
+typedef int __attribute__((vector_size(32))) int8;
+typedef float __attribute__((vector_size(32))) float8;
+typedef double __attribute__((vector_size(32))) double4;
+
+int8 test_vector_int8(int cond, int8 a, int8 b) {
+ // CHECK-LABEL: define {{.*}} @test_vector_int8
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[RESULT:%.*]] = call <8 x i32> @llvm.ct.select.v8i32(i1 [[COND]], <8 x i32> %{{.*}}, <8 x i32> %{{.*}})
+ return __builtin_ct_select(cond, a, b);
+}
+
+float8 test_vector_float8(int cond, float8 a, float8 b) {
+ // CHECK-LABEL: define {{.*}} @test_vector_float8
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[RESULT:%.*]] = call <8 x float> @llvm.ct.select.v8f32(i1 [[COND]], <8 x float> %{{.*}}, <8 x float> %{{.*}})
+ return __builtin_ct_select(cond, a, b);
+}
+
+double4 test_vector_double4(int cond, double4 a, double4 b) {
+ // CHECK-LABEL: define {{.*}} @test_vector_double4
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[RESULT:%.*]] = call <4 x double> @llvm.ct.select.v4f64(i1 [[COND]], <4 x double> %{{.*}}, <4 x double> %{{.*}})
+ return __builtin_ct_select(cond, a, b);
+}
+
+// Test 512-bit vectors
+typedef int __attribute__((vector_size(64))) int16;
+typedef float __attribute__((vector_size(64))) float16;
+
+int16 test_vector_int16(int cond, int16 a, int16 b) {
+ // CHECK-LABEL: define {{.*}} @test_vector_int16
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call <16 x i32> @llvm.ct.select.v16i32(i1 [[COND]], <16 x i32> %{{.*}}, <16 x i32> %{{.*}})
+ return __builtin_ct_select(cond, a, b);
+}
+
+float16 test_vector_float16(int cond, float16 a, float16 b) {
+ // CHECK-LABEL: define {{.*}} @test_vector_float16
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call <16 x float> @llvm.ct.select.v16f32(i1 [[COND]], <16 x float> %{{.*}}, <16 x float> %{{.*}})
+ return __builtin_ct_select(cond, a, b);
+}
+
+// Test vector operations with different condition types
+int4 test_vector_char_cond(char cond, int4 a, int4 b) {
+ // CHECK-LABEL: define {{.*}} @test_vector_char_cond
+ // CHECK: [[COND:%.*]] = icmp ne i8 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call <4 x i32> @llvm.ct.select.v4i32(i1 [[COND]], <4 x i32> %{{.*}}, <4 x i32> %{{.*}})
+ // CHECK: ret <4 x i32> [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+float4 test_vector_long_cond(long long cond, float4 a, float4 b) {
+ // CHECK-LABEL: define {{.*}} @test_vector_long_cond
+ // CHECK: [[COND:%.*]] = icmp ne i64 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call <4 x float> @llvm.ct.select.v4f32(i1 [[COND]], <4 x float> %{{.*}}, <4 x float> %{{.*}})
+ // CHECK: ret <4 x float> [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+// Test vector constants
+int4 test_vector_constant_cond(void) {
+ // CHECK-LABEL: define {{.*}} @test_vector_constant_cond
+ // CHECK: [[RESULT:%.*]] = call <4 x i32> @llvm.ct.select.v4i32(i1 true, <4 x i32> %{{.*}}, <4 x i32> %{{.*}})
+ // CHECK: ret <4 x i32> [[RESULT]]
+ int4 a = {1, 2, 3, 4};
+ int4 b = {5, 6, 7, 8};
+ return __builtin_ct_select(1, a, b);
+}
+
+float4 test_vector_zero_cond(void) {
+ // CHECK-LABEL: define {{.*}} @test_vector_zero_cond
+ // CHECK: [[RESULT:%.*]] = call <4 x float> @llvm.ct.select.v4f32(i1 false, <4 x float> %{{.*}}, <4 x float> %{{.*}})
+ // CHECK: ret <4 x float> [[RESULT]]
+ float4 a = {1.0f, 2.0f, 3.0f, 4.0f};
+ float4 b = {5.0f, 6.0f, 7.0f, 8.0f};
+ return __builtin_ct_select(0, a, b);
+}
+
+// Test nested vector selections
+int4 test_vector_nested(int cond1, int cond2, int4 a, int4 b, int4 c) {
+ // CHECK-LABEL: define {{.*}} @test_vector_nested
+ // CHECK-DAG: [[COND1:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[COND2:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[INNER:%.*]] = call <4 x i32> @llvm.ct.select.v4i32(i1 [[COND2]], <4 x i32> %{{.*}}, <4 x i32> %{{.*}})
+ // CHECK: [[RESULT:%.*]] = call <4 x i32> @llvm.ct.select.v4i32(i1 [[COND1]], <4 x i32> [[INNER]], <4 x i32> %{{.*}})
+ // CHECK: ret <4 x i32> [[RESULT]]
+ return __builtin_ct_select(cond1, __builtin_ct_select(cond2, a, b), c);
+}
+
+// Test vector selection with complex expressions
+float4 test_vector_complex_expr(int x, int y, float4 a, float4 b) {
+ // CHECK-LABEL: define {{.*}} @test_vector_complex_expr
+ // CHECK: [[CMP:%.*]] = icmp sgt i32 %{{.*}}, %{{.*}}
+ // CHECK: [[RESULT:%.*]] = call <4 x float> @llvm.ct.select.v4f32(i1 [[CMP]], <4 x float> %{{.*}}, <4 x float> %{{.*}})
+ // CHECK: ret <4 x float> [[RESULT]]
+ return __builtin_ct_select(x > y, a, b);
+}
+
+// Test vector with different element sizes
+typedef long long __attribute__((vector_size(16))) long2;
+typedef double __attribute__((vector_size(16))) double2;
+
+long2 test_vector_long2(int cond, long2 a, long2 b) {
+ // CHECK-LABEL: define {{.*}} @test_vector_long2
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call <2 x i64> @llvm.ct.select.v2i64(i1 [[COND]], <2 x i64> %{{.*}}, <2 x i64> %{{.*}})
+ // CHECK: ret <2 x i64> [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+double2 test_vector_double2(int cond, double2 a, double2 b) {
+ // CHECK-LABEL: define {{.*}} @test_vector_double2
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call <2 x double> @llvm.ct.select.v2f64(i1 [[COND]], <2 x double> %{{.*}}, <2 x double> %{{.*}})
+ // CHECK: ret <2 x double> [[RESULT]]
+ return __builtin_ct_select(cond, a, b);
+}
+
+// Test mixed vector operations
+int4 test_vector_from_scalar_condition(int4 vec_cond, int4 a, int4 b) {
+ // CHECK-LABEL: define {{.*}} @test_vector_from_scalar_condition
+ // Extract first element and use as condition
+ int scalar_cond = vec_cond[0];
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call <4 x i32> @llvm.ct.select.v4i32(i1 [[COND]], <4 x i32> %{{.*}}, <4 x i32> %{{.*}})
+ // CHECK: ret <4 x i32> [[RESULT]]
+ return __builtin_ct_select(scalar_cond, a, b);
+}
+
+// Test vector chaining
+float4 test_vector_chaining(int cond1, int cond2, int cond3, float4 a, float4 b, float4 c, float4 d) {
+ // CHECK-LABEL: define {{.*}} @test_vector_chaining
+ // CHECK-DAG: [[COND1:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[COND2:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[COND3:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[FIRST:%.*]] = call <4 x float> @llvm.ct.select.v4f32(i1 [[COND1]], <4 x float> %{{.*}}, <4 x float> %{{.*}})
+ // CHECK-DAG: [[SECOND:%.*]] = call <4 x float> @llvm.ct.select.v4f32(i1 [[COND2]], <4 x float> %{{.*}}, <4 x float> %{{.*}})
+ // CHECK-DAG: [[RESULT:%.*]] = call <4 x float> @llvm.ct.select.v4f32(i1 [[COND3]], <4 x float> %{{.*}}, <4 x float> %{{.*}})
+ // CHECK: ret <4 x float> [[RESULT]]
+ float4 first = __builtin_ct_select(cond1, a, b);
+ float4 second = __builtin_ct_select(cond2, first, c);
+ return __builtin_ct_select(cond3, second, d);
+}
+
+// Test special floating point values - NaN
+float test_nan_operands(int cond) {
+ // CHECK-LABEL: define {{.*}} @test_nan_operands
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[RESULT:%.*]] = call float @llvm.ct.select.f32(i1 [[COND]], float %{{.*}}, float 1.000000e+00)
+ // CHECK: ret float [[RESULT]]
+ float nan_val = __builtin_nanf("");
+ return __builtin_ct_select(cond, nan_val, 1.0f);
+}
+
+double test_nan_double_operands(int cond) {
+ // CHECK-LABEL: define {{.*}} @test_nan_double_operands
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[RESULT:%.*]] = call double @llvm.ct.select.f64(i1 [[COND]], double %{{.*}}, double 2.000000e+00)
+ // CHECK: ret double [[RESULT]]
+ double nan_val = __builtin_nan("");
+ return __builtin_ct_select(cond, nan_val, 2.0);
+}
+
+// Test infinity values
+float test_infinity_operands(int cond) {
+ // CHECK-LABEL: define {{.*}} @test_infinity_operands
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[RESULT:%.*]] = call float @llvm.ct.select.f32(i1 [[COND]], float %{{.*}}, float %{{.*}})
+ // CHECK: ret float [[RESULT]]
+ float pos_inf = __builtin_inff();
+ float neg_inf = -__builtin_inff();
+ return __builtin_ct_select(cond, pos_inf, neg_inf);
+}
+
+double test_infinity_double_operands(int cond) {
+ // CHECK-LABEL: define {{.*}} @test_infinity_double_operands
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[RESULT:%.*]] = call double @llvm.ct.select.f64(i1 [[COND]], double %{{.*}}, double %{{.*}})
+ // CHECK: ret double [[RESULT]]
+ double pos_inf = __builtin_inf();
+ double neg_inf = -__builtin_inf();
+ return __builtin_ct_select(cond, pos_inf, neg_inf);
+}
+
+// Test subnormal/denormal values
+float test_subnormal_operands(int cond) {
+ // CHECK-LABEL: define {{.*}} @test_subnormal_operands
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[RESULT:%.*]] = call float @llvm.ct.select.f32(i1 [[COND]], float %{{.*}}, float %{{.*}})
+ // CHECK: ret float [[RESULT]]
+ // Very small subnormal values
+ float subnormal1 = 1e-40f;
+ float subnormal2 = 1e-45f;
+ return __builtin_ct_select(cond, subnormal1, subnormal2);
+}
+
+// Test integer overflow boundaries
+int test_integer_overflow_operands(int cond) {
+ // CHECK-LABEL: define {{.*}} @test_integer_overflow_operands
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: ret i32 [[RESULT]]
+ int max_int = __INT_MAX__;
+ int min_int = (-__INT_MAX__ - 1);
+ return __builtin_ct_select(cond, max_int, min_int);
+}
+
+long long test_longlong_overflow_operands(int cond) {
+ // CHECK-LABEL: define {{.*}} @test_longlong_overflow_operands
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[RESULT:%.*]] = call i64 @llvm.ct.select.i64(i1 [[COND]], i64 %{{.*}}, i64 %{{.*}})
+ // CHECK: ret i64 [[RESULT]]
+ long long max_ll = __LONG_LONG_MAX__;
+ long long min_ll = (-__LONG_LONG_MAX__ - 1);
+ return __builtin_ct_select(cond, max_ll, min_ll);
+}
+
+// Test unsigned overflow boundaries
+unsigned int test_unsigned_overflow_operands(int cond) {
+ // CHECK-LABEL: define {{.*}} @test_unsigned_overflow_operands
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: ret i32 [[RESULT]]
+ unsigned int max_uint = 4294967295;
+ unsigned int min_uint = 0;
+ return __builtin_ct_select(cond, max_uint, min_uint);
+}
+
+// Test null pointer dereference avoidance
+int* test_null_pointer_operands(int cond, int* valid_ptr) {
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call ptr @llvm.ct.select.p0(i1 [[COND]], ptr %{{.*}}, ptr %{{.*}})
+ // CHECK: ret ptr [[RESULT]]
+ int* null_ptr = (int*)0;
+ return __builtin_ct_select(cond, null_ptr, valid_ptr);
+}
+
+// Test volatile operations
+volatile int global_volatile = 42;
+int test_volatile_operands(int cond) {
+ // CHECK-LABEL: define {{.*}} @test_volatile_operands
+ // CHECK-DAG: [[VOLATILE_LOAD:%.*]] = load volatile i32, ptr {{.*}}
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND]], i32 %{{.*}}, i32 100)
+ // CHECK: ret i32 [[RESULT]]
+ volatile int vol_val = global_volatile;
+ return __builtin_ct_select(cond, vol_val, 100);
+}
+
+// Test uninitialized variable behavior (should still work with ct_select)
+int test_uninitialized_operands(int cond, int initialized) {
+ // CHECK-LABEL: define {{.*}} @test_uninitialized_operands
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: ret i32 [[RESULT]]
+ int uninitialized; // Intentionally uninitialized
+ return __builtin_ct_select(cond, uninitialized, initialized);
+}
+
+// Test zero division avoidance patterns
+int test_division_by_zero_avoidance(int cond, int dividend, int divisor) {
+ // CHECK-LABEL: define {{.*}} @test_division_by_zero_avoidance
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[DIV_RESULT:%.*]] = sdiv i32 %{{.*}}, %{{.*}}
+ // CHECK-DAG: [[SAFE_DIVISOR:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND]], i32 %{{.*}}, i32 1)
+ // First get a safe divisor (never zero)
+ int safe_divisor = __builtin_ct_select(divisor != 0, divisor, 1);
+ // Then perform division with guaranteed non-zero divisor
+ return dividend / safe_divisor;
+}
+
+// Test array bounds checking patterns
+int test_array_bounds_protection(int cond, int index, int* array) {
+ // CHECK-LABEL: define {{.*}} @test_array_bounds_protection
+ // CHECK-DAG: [[SAFE_INDEX:%.*]] = call i32 @llvm.ct.select.i32(i1 {{.*}}, i32 %{{.*}}, i32 0)
+ // Use ct_select to ensure safe array indexing
+ int safe_index = __builtin_ct_select(index >= 0 && index < 10, index, 0);
+ return array[safe_index];
+}
+
+// Test bit manipulation edge cases
+unsigned int test_bit_manipulation_edge_cases(int cond, unsigned int value) {
+ // CHECK-LABEL: define {{.*}} @test_bit_manipulation_edge_cases
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[SHIFT_LEFT:%.*]] = shl i32 %{{.*}}, 31
+ // CHECK-DAG: [[SHIFT_RIGHT:%.*]] = lshr i32 %{{.*}}, 31
+ // CHECK-DAG: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: ret i32 [[RESULT]]
+ // Test extreme bit shifts that could cause undefined behavior
+ unsigned int left_shift = value << 31; // Could overflow
+ unsigned int right_shift = value >> 31; // Extract sign bit
+ return __builtin_ct_select(cond, left_shift, right_shift);
+}
+
+// Test signed integer wraparound
+int test_signed_wraparound(int cond, int a, int b) {
+ // CHECK-LABEL: define {{.*}} @test_signed_wraparound
+ // CHECK-DAG: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK-DAG: [[ADD:%.*]] = add nsw i32 %{{.*}}, %{{.*}}
+ // CHECK-DAG: [[SUB:%.*]] = sub nsw i32 %{{.*}}, %{{.*}}
+ // CHECK-DAG: [[RESULT:%.*]] = call i32 @llvm.ct.select.i32(i1 [[COND]], i32 %{{.*}}, i32 %{{.*}})
+ // CHECK: ret i32 [[RESULT]]
+ int sum = a + b; // Could overflow
+ int diff = a - b; // Could underflow
+ return __builtin_ct_select(cond, sum, diff);
+}
+
+// Test vector NaN handling
+float4 test_vector_nan_operands(int cond) {
+ // CHECK-LABEL: define {{.*}} @test_vector_nan_operands
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call <4 x float> @llvm.ct.select.v4f32(i1 [[COND]], <4 x float> %{{.*}}, <4 x float> %{{.*}})
+ // CHECK: ret <4 x float> [[RESULT]]
+ float nan_val = __builtin_nanf("");
+ float4 nan_vec = {nan_val, nan_val, nan_val, nan_val};
+ float4 normal_vec = {1.0f, 2.0f, 3.0f, 4.0f};
+ return __builtin_ct_select(cond, nan_vec, normal_vec);
+}
+
+// Test vector infinity handling
+float4 test_vector_infinity_operands(int cond) {
+ // CHECK-LABEL: define {{.*}} @test_vector_infinity_operands
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call <4 x float> @llvm.ct.select.v4f32(i1 [[COND]], <4 x float> %{{.*}}, <4 x float> %{{.*}})
+ // CHECK: ret <4 x float> [[RESULT]]
+ float pos_inf = __builtin_inff();
+ float neg_inf = -__builtin_inff();
+ float4 inf_vec = {pos_inf, neg_inf, pos_inf, neg_inf};
+ float4 zero_vec = {0.0f, 0.0f, 0.0f, 0.0f};
+ return __builtin_ct_select(cond, inf_vec, zero_vec);
+}
+
+// Test mixed special values
+double test_mixed_special_values(int cond) {
+ // CHECK-LABEL: define {{.*}} @test_mixed_special_values
+ // CHECK: [[COND:%.*]] = icmp ne i32 %{{.*}}, 0
+ // CHECK: [[RESULT:%.*]] = call double @llvm.ct.select.f64(i1 [[COND]], double %{{.*}}, double %{{.*}})
+ // CHECK: ret double [[RESULT]]
+ double nan_val = __builtin_nan("");
+ double inf_val = __builtin_inf();
+ return __builtin_ct_select(cond, nan_val, inf_val);
+}
+
+// Test constant-time memory access pattern
+int test_constant_time_memory_access(int secret_index, int* data_array) {
+ // CHECK-LABEL: define {{.*}} @test_constant_time_memory_access
+ // This pattern ensures constant-time memory access regardless of secret_index value
+ int result = 0;
+ // Use ct_select to accumulate values without revealing the secret index
+ for (int i = 0; i < 8; i++) {
+ int is_target = (i == secret_index);
+ int current_value = data_array[i];
+ int selected_value = __builtin_ct_select(is_target, current_value, 0);
+ result += selected_value;
+ }
+ return result;
+}
+
+// Test timing-attack resistant comparison
+int test_timing_resistant_comparison(const char* secret, const char* guess) {
+ // CHECK-LABEL: define {{.*}} @test_timing_resistant_comparison
+ // Constant-time string comparison using ct_select
+ int match = 1;
+ for (int i = 0; i < 32; i++) {
+ int chars_equal = (secret[i] == guess[i]);
+ int both_null = (secret[i] == 0) && (guess[i] == 0);
+ int still_matching = __builtin_ct_select(chars_equal || both_null, match, 0);
+ match = __builtin_ct_select(both_null, match, still_matching);
+ }
+ return match;
+}
>From 056e570fe0667f074bc61fd85163157ab59341d9 Mon Sep 17 00:00:00 2001
From: wizardengineer <juliuswoosebert at gmail.com>
Date: Wed, 5 Nov 2025 17:09:45 -0500
Subject: [PATCH 2/3] [LLVM][AArch64] Add native ct.select support for ARM64
This patch implements architecture-specific lowering for ct.select on AArch64
using CSEL (conditional select) instructions for constant-time selection.
Implementation details:
- Uses CSEL family of instructions for scalar integer types
- Uses FCSEL for floating-point types (F16, BF16, F32, F64)
- Post-RA MC lowering to convert pseudo-instructions to real CSEL/FCSEL
- Handles vector types appropriately
- Comprehensive test coverage for AArch64
The implementation includes:
- ISelLowering: Custom lowering to CTSELECT pseudo-instructions
- InstrInfo: Pseudo-instruction definitions and patterns
- MCInstLower: Post-RA lowering of pseudo-instructions to actual CSEL/FCSEL
- Proper handling of condition codes for constant-time guarantees
---
.../Target/AArch64/AArch64ISelLowering.cpp | 56 +++++++
llvm/lib/Target/AArch64/AArch64ISelLowering.h | 11 ++
llvm/lib/Target/AArch64/AArch64InstrInfo.cpp | 39 ++++-
llvm/lib/Target/AArch64/AArch64InstrInfo.td | 40 +++++
.../lib/Target/AArch64/AArch64MCInstLower.cpp | 18 +++
llvm/test/CodeGen/AArch64/ctselect.ll | 139 ++++++++++++++++++
6 files changed, 299 insertions(+), 4 deletions(-)
create mode 100644 llvm/test/CodeGen/AArch64/ctselect.ll
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index f91053ec4a89a..42558c2d2136b 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -532,12 +532,36 @@ AArch64TargetLowering::AArch64TargetLowering(const TargetMachine &TM,
setOperationAction(ISD::BR_CC, MVT::f64, Custom);
setOperationAction(ISD::SELECT, MVT::i32, Custom);
setOperationAction(ISD::SELECT, MVT::i64, Custom);
+ setOperationAction(ISD::CT_SELECT, MVT::i8, Promote);
+ setOperationAction(ISD::CT_SELECT, MVT::i16, Promote);
+ setOperationAction(ISD::CT_SELECT, MVT::i32, Custom);
+ setOperationAction(ISD::CT_SELECT, MVT::i64, Custom);
if (Subtarget->hasFPARMv8()) {
setOperationAction(ISD::SELECT, MVT::f16, Custom);
setOperationAction(ISD::SELECT, MVT::bf16, Custom);
}
+ if (Subtarget->hasFullFP16()) {
+ setOperationAction(ISD::CT_SELECT, MVT::f16, Custom);
+ setOperationAction(ISD::CT_SELECT, MVT::bf16, Custom);
+ } else {
+ setOperationAction(ISD::CT_SELECT, MVT::f16, Promote);
+ setOperationAction(ISD::CT_SELECT, MVT::bf16, Promote);
+ }
setOperationAction(ISD::SELECT, MVT::f32, Custom);
setOperationAction(ISD::SELECT, MVT::f64, Custom);
+ setOperationAction(ISD::CT_SELECT, MVT::f32, Custom);
+ setOperationAction(ISD::CT_SELECT, MVT::f64, Custom);
+ for (MVT VT : MVT::vector_valuetypes()) {
+ MVT elemType = VT.getVectorElementType();
+ if (elemType == MVT::i8 || elemType == MVT::i16) {
+ setOperationAction(ISD::CT_SELECT, VT, Promote);
+ } else if ((elemType == MVT::f16 || elemType == MVT::bf16) &&
+ !Subtarget->hasFullFP16()) {
+ setOperationAction(ISD::CT_SELECT, VT, Promote);
+ } else {
+ setOperationAction(ISD::CT_SELECT, VT, Expand);
+ }
+ }
setOperationAction(ISD::SELECT_CC, MVT::i32, Custom);
setOperationAction(ISD::SELECT_CC, MVT::i64, Custom);
setOperationAction(ISD::SELECT_CC, MVT::f16, Custom);
@@ -3427,6 +3451,20 @@ void AArch64TargetLowering::fixupPtrauthDiscriminator(
IntDiscOp.setImm(IntDisc);
}
+MachineBasicBlock *AArch64TargetLowering::EmitCTSELECT(MachineInstr &MI,
+ MachineBasicBlock *MBB,
+ unsigned Opcode) const {
+ const TargetInstrInfo *TII = Subtarget->getInstrInfo();
+ DebugLoc DL = MI.getDebugLoc();
+ MachineInstrBuilder Builder = BuildMI(*MBB, MI, DL, TII->get(Opcode));
+ for (unsigned Idx = 0; Idx < MI.getNumOperands(); ++Idx) {
+ Builder.add(MI.getOperand(Idx));
+ }
+ Builder->setFlag(MachineInstr::NoMerge);
+ MBB->remove_instr(&MI);
+ return MBB;
+}
+
MachineBasicBlock *AArch64TargetLowering::EmitInstrWithCustomInserter(
MachineInstr &MI, MachineBasicBlock *BB) const {
@@ -8284,6 +8322,8 @@ SDValue AArch64TargetLowering::LowerOperation(SDValue Op,
return LowerSELECT(Op, DAG);
case ISD::SELECT_CC:
return LowerSELECT_CC(Op, DAG);
+ case ISD::CT_SELECT:
+ return LowerCTSELECT(Op, DAG);
case ISD::JumpTable:
return LowerJumpTable(Op, DAG);
case ISD::BR_JT:
@@ -12710,6 +12750,22 @@ SDValue AArch64TargetLowering::LowerSELECT(SDValue Op,
return Res;
}
+SDValue AArch64TargetLowering::LowerCTSELECT(SDValue Op,
+ SelectionDAG &DAG) const {
+ SDValue CCVal = Op->getOperand(0);
+ SDValue TVal = Op->getOperand(1);
+ SDValue FVal = Op->getOperand(2);
+ SDLoc DL(Op);
+
+ EVT VT = Op.getValueType();
+
+ SDValue Zero = DAG.getConstant(0, DL, CCVal.getValueType());
+ SDValue CC;
+ SDValue Cmp = getAArch64Cmp(CCVal, Zero, ISD::SETNE, CC, DAG, DL);
+
+ return DAG.getNode(AArch64ISD::CT_SELECT, DL, VT, TVal, FVal, CC, Cmp);
+}
+
SDValue AArch64TargetLowering::LowerJumpTable(SDValue Op,
SelectionDAG &DAG) const {
// Jump table entries as PC relative offsets. No additional tweaking
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.h b/llvm/lib/Target/AArch64/AArch64ISelLowering.h
index 3a93d9a3c0d1e..d1728cd54ed77 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.h
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.h
@@ -23,6 +23,11 @@
namespace llvm {
+namespace AArch64ISD {
+// Forward declare the enum from the generated file
+enum GenNodeType : unsigned;
+} // namespace AArch64ISD
+
class AArch64TargetMachine;
namespace AArch64 {
@@ -200,6 +205,9 @@ class AArch64TargetLowering : public TargetLowering {
MachineOperand &AddrDiscOp,
const TargetRegisterClass *AddrDiscRC) const;
+ MachineBasicBlock *EmitCTSELECT(MachineInstr &MI, MachineBasicBlock *BB,
+ unsigned Opcode) const;
+
MachineBasicBlock *
EmitInstrWithCustomInserter(MachineInstr &MI,
MachineBasicBlock *MBB) const override;
@@ -714,6 +722,7 @@ class AArch64TargetLowering : public TargetLowering {
iterator_range<SDNode::user_iterator> Users,
SDNodeFlags Flags, const SDLoc &dl,
SelectionDAG &DAG) const;
+ SDValue LowerCTSELECT(SDValue Op, SelectionDAG &DAG) const;
SDValue LowerINIT_TRAMPOLINE(SDValue Op, SelectionDAG &DAG) const;
SDValue LowerADJUST_TRAMPOLINE(SDValue Op, SelectionDAG &DAG) const;
SDValue LowerJumpTable(SDValue Op, SelectionDAG &DAG) const;
@@ -948,6 +957,8 @@ class AArch64TargetLowering : public TargetLowering {
bool hasMultipleConditionRegisters(EVT VT) const override {
return VT.isScalableVector();
}
+
+ bool isSelectSupported(SelectSupportKind Kind) const override { return true; }
};
namespace AArch64 {
diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
index bd521d8e7856c..e90ca1babba21 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -2479,16 +2479,47 @@ bool AArch64InstrInfo::removeCmpToZeroOrOne(
return true;
}
-bool AArch64InstrInfo::expandPostRAPseudo(MachineInstr &MI) const {
- if (MI.getOpcode() != TargetOpcode::LOAD_STACK_GUARD &&
- MI.getOpcode() != AArch64::CATCHRET)
- return false;
+static inline void expandCtSelect(MachineBasicBlock &MBB, MachineInstr &MI,
+ DebugLoc &DL, const MCInstrDesc &MCID) {
+ MachineInstrBuilder Builder = BuildMI(MBB, MI, DL, MCID);
+ for (unsigned Idx = 0; Idx < MI.getNumOperands(); ++Idx) {
+ Builder.add(MI.getOperand(Idx));
+ }
+ Builder->setFlag(MachineInstr::NoMerge);
+ MBB.remove_instr(&MI);
+}
+bool AArch64InstrInfo::expandPostRAPseudo(MachineInstr &MI) const {
MachineBasicBlock &MBB = *MI.getParent();
auto &Subtarget = MBB.getParent()->getSubtarget<AArch64Subtarget>();
auto TRI = Subtarget.getRegisterInfo();
DebugLoc DL = MI.getDebugLoc();
+ switch (MI.getOpcode()) {
+ case AArch64::I32CTSELECT:
+ expandCtSelect(MBB, MI, DL, get(AArch64::CSELWr));
+ return true;
+ case AArch64::I64CTSELECT:
+ expandCtSelect(MBB, MI, DL, get(AArch64::CSELXr));
+ return true;
+ case AArch64::BF16CTSELECT:
+ expandCtSelect(MBB, MI, DL, get(AArch64::FCSELHrrr));
+ return true;
+ case AArch64::F16CTSELECT:
+ expandCtSelect(MBB, MI, DL, get(AArch64::FCSELHrrr));
+ return true;
+ case AArch64::F32CTSELECT:
+ expandCtSelect(MBB, MI, DL, get(AArch64::FCSELSrrr));
+ return true;
+ case AArch64::F64CTSELECT:
+ expandCtSelect(MBB, MI, DL, get(AArch64::FCSELDrrr));
+ return true;
+ }
+
+ if (MI.getOpcode() != TargetOpcode::LOAD_STACK_GUARD &&
+ MI.getOpcode() != AArch64::CATCHRET)
+ return false;
+
if (MI.getOpcode() == AArch64::CATCHRET) {
// Skip to the first instruction before the epilog.
const TargetInstrInfo *TII =
diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.td b/llvm/lib/Target/AArch64/AArch64InstrInfo.td
index 9db82fa86348e..5240458ca8020 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.td
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.td
@@ -478,6 +478,9 @@ def SDT_AArch64cbz : SDTypeProfile<0, 2, [SDTCisInt<0>, SDTCisVT<1, OtherVT>]>;
def SDT_AArch64tbz : SDTypeProfile<0, 3, [SDTCisInt<0>, SDTCisInt<1>,
SDTCisVT<2, OtherVT>]>;
+def SDT_AArch64CtSelect : SDTypeProfile<1, 4,
+ [SDTCisSameAs<0, 1>, SDTCisSameAs<0, 2>,
+ SDTCisInt<3>, SDTCisVT<4, i32>]>;
def SDT_AArch64CSel : SDTypeProfile<1, 4,
[SDTCisSameAs<0, 1>,
SDTCisSameAs<0, 2>,
@@ -845,6 +848,7 @@ def AArch64tbz : SDNode<"AArch64ISD::TBZ", SDT_AArch64tbz,
def AArch64tbnz : SDNode<"AArch64ISD::TBNZ", SDT_AArch64tbz,
[SDNPHasChain]>;
+def AArch64ctselect : SDNode<"AArch64ISD::CT_SELECT", SDT_AArch64CtSelect>;
def AArch64csel : SDNode<"AArch64ISD::CSEL", SDT_AArch64CSel>;
// Conditional select invert.
@@ -5724,6 +5728,42 @@ def F128CSEL : Pseudo<(outs FPR128:$Rd),
let hasNoSchedulingInfo = 1;
}
+//===----------------------------------------------------------------------===//
+// Constant-time conditional selection instructions
+//===----------------------------------------------------------------------===//
+
+let hasSideEffects = 1, isPseudo = 1, hasNoSchedulingInfo = 1,
+ Uses = [NZCV] in {
+ def I32CTSELECT
+ : Pseudo<(outs GPR32:$dst), (ins GPR32:$tval, GPR32:$fval, i32imm:$cc),
+ [(set (i32 GPR32:$dst), (AArch64ctselect GPR32:$tval,
+ GPR32:$fval, (i32 imm:$cc), NZCV))]>;
+ def I64CTSELECT
+ : Pseudo<(outs GPR64:$dst), (ins GPR64:$tval, GPR64:$fval, i32imm:$cc),
+ [(set (i64 GPR64:$dst), (AArch64ctselect GPR64:$tval,
+ GPR64:$fval, (i32 imm:$cc), NZCV))]>;
+ let Predicates = [HasFullFP16] in {
+ def F16CTSELECT
+ : Pseudo<(outs FPR16:$dst), (ins FPR16:$tval, FPR16:$fval, i32imm:$cc),
+ [(set (f16 FPR16:$dst), (AArch64ctselect (f16 FPR16:$tval),
+ (f16 FPR16:$fval), (i32 imm:$cc),
+ NZCV))]>;
+ def BF16CTSELECT
+ : Pseudo<(outs FPR16:$dst), (ins FPR16:$tval, FPR16:$fval, i32imm:$cc),
+ [(set (bf16 FPR16:$dst), (AArch64ctselect (bf16 FPR16:$tval),
+ (bf16 FPR16:$fval), (i32 imm:$cc),
+ NZCV))]>;
+ }
+ def F32CTSELECT
+ : Pseudo<(outs FPR32:$dst), (ins FPR32:$tval, FPR32:$fval, i32imm:$cc),
+ [(set (f32 FPR32:$dst), (AArch64ctselect FPR32:$tval,
+ FPR32:$fval, (i32 imm:$cc), NZCV))]>;
+ def F64CTSELECT
+ : Pseudo<(outs FPR64:$dst), (ins FPR64:$tval, FPR64:$fval, i32imm:$cc),
+ [(set (f64 FPR64:$dst), (AArch64ctselect FPR64:$tval,
+ FPR64:$fval, (i32 imm:$cc), NZCV))]>;
+}
+
//===----------------------------------------------------------------------===//
// Instructions used for emitting unwind opcodes on ARM64 Windows.
//===----------------------------------------------------------------------===//
diff --git a/llvm/lib/Target/AArch64/AArch64MCInstLower.cpp b/llvm/lib/Target/AArch64/AArch64MCInstLower.cpp
index d3a38624488e8..46e3615c63905 100644
--- a/llvm/lib/Target/AArch64/AArch64MCInstLower.cpp
+++ b/llvm/lib/Target/AArch64/AArch64MCInstLower.cpp
@@ -393,5 +393,23 @@ void AArch64MCInstLower::Lower(const MachineInstr *MI, MCInst &OutMI) const {
OutMI.setOpcode(AArch64::RET);
OutMI.addOperand(MCOperand::createReg(AArch64::LR));
break;
+ case AArch64::I32CTSELECT:
+ OutMI.setOpcode(AArch64::CSELWr);
+ break;
+ case AArch64::I64CTSELECT:
+ OutMI.setOpcode(AArch64::CSELXr);
+ break;
+ case AArch64::BF16CTSELECT:
+ OutMI.setOpcode(AArch64::FCSELHrrr);
+ break;
+ case AArch64::F16CTSELECT:
+ OutMI.setOpcode(AArch64::FCSELHrrr);
+ break;
+ case AArch64::F32CTSELECT:
+ OutMI.setOpcode(AArch64::FCSELSrrr);
+ break;
+ case AArch64::F64CTSELECT:
+ OutMI.setOpcode(AArch64::FCSELDrrr);
+ break;
}
}
diff --git a/llvm/test/CodeGen/AArch64/ctselect.ll b/llvm/test/CodeGen/AArch64/ctselect.ll
new file mode 100644
index 0000000000000..4df452b05af72
--- /dev/null
+++ b/llvm/test/CodeGen/AArch64/ctselect.ll
@@ -0,0 +1,139 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 6
+; RUN: llc < %s -verify-machineinstrs -mtriple=aarch64-none-eabi | FileCheck %s --check-prefixes=DEFAULT,NOFP16
+; RUN: llc < %s -verify-machineinstrs -mtriple=aarch64-none-eabi -mattr=+fullfp16 | FileCheck %s --check-prefixes=DEFAULT,FP16
+
+define i1 @ct_i1(i1 %cond, i1 %a, i1 %b) {
+; DEFAULT-LABEL: ct_i1:
+; DEFAULT: // %bb.0:
+; DEFAULT-NEXT: tst w0, #0x1
+; DEFAULT-NEXT: csel w8, w1, w2, ne
+; DEFAULT-NEXT: and w0, w8, #0x1
+; DEFAULT-NEXT: ret
+ %1 = call i1 @llvm.ct.select.i1(i1 %cond, i1 %a, i1 %b)
+ ret i1 %1
+}
+
+define i8 @ct_i8(i1 %cond, i8 %a, i8 %b) {
+; DEFAULT-LABEL: ct_i8:
+; DEFAULT: // %bb.0:
+; DEFAULT-NEXT: tst w0, #0x1
+; DEFAULT-NEXT: csel w0, w1, w2, ne
+; DEFAULT-NEXT: ret
+ %1 = call i8 @llvm.ct.select.i8(i1 %cond, i8 %a, i8 %b)
+ ret i8 %1
+}
+
+define i16 @ct_i16(i1 %cond, i16 %a, i16 %b) {
+; DEFAULT-LABEL: ct_i16:
+; DEFAULT: // %bb.0:
+; DEFAULT-NEXT: tst w0, #0x1
+; DEFAULT-NEXT: csel w0, w1, w2, ne
+; DEFAULT-NEXT: ret
+ %1 = call i16 @llvm.ct.select.i16(i1 %cond, i16 %a, i16 %b)
+ ret i16 %1
+}
+
+define i32 @ct_i32(i1 %cond, i32 %a, i32 %b) {
+; DEFAULT-LABEL: ct_i32:
+; DEFAULT: // %bb.0:
+; DEFAULT-NEXT: tst w0, #0x1
+; DEFAULT-NEXT: csel w0, w1, w2, ne
+; DEFAULT-NEXT: ret
+ %1 = call i32 @llvm.ct.select.i32(i1 %cond, i32 %a, i32 %b)
+ ret i32 %1
+}
+
+define i64 @ct_i64(i1 %cond, i64 %a, i64 %b) {
+; DEFAULT-LABEL: ct_i64:
+; DEFAULT: // %bb.0:
+; DEFAULT-NEXT: tst w0, #0x1
+; DEFAULT-NEXT: csel x0, x1, x2, ne
+; DEFAULT-NEXT: ret
+ %1 = call i64 @llvm.ct.select.i64(i1 %cond, i64 %a, i64 %b)
+ ret i64 %1
+}
+
+define i128 @ct_i128(i1 %cond, i128 %a, i128 %b) {
+; DEFAULT-LABEL: ct_i128:
+; DEFAULT: // %bb.0:
+; DEFAULT-NEXT: tst w0, #0x1
+; DEFAULT-NEXT: csel x0, x2, x4, ne
+; DEFAULT-NEXT: csel x1, x3, x5, ne
+; DEFAULT-NEXT: ret
+ %1 = call i128 @llvm.ct.select.i128(i1 %cond, i128 %a, i128 %b)
+ ret i128 %1
+}
+
+define half @ct_f16(i1 %cond, half %a, half %b) {
+; NOFP16-LABEL: ct_f16:
+; NOFP16: // %bb.0:
+; NOFP16-NEXT: // kill: def $h1 killed $h1 def $s1
+; NOFP16-NEXT: // kill: def $h0 killed $h0 def $s0
+; NOFP16-NEXT: fmov w9, s0
+; NOFP16-NEXT: fmov w10, s1
+; NOFP16-NEXT: sbfx w8, w0, #0, #1
+; NOFP16-NEXT: bic w10, w10, w8
+; NOFP16-NEXT: and w8, w9, w8
+; NOFP16-NEXT: orr w8, w8, w10
+; NOFP16-NEXT: fmov s0, w8
+; NOFP16-NEXT: // kill: def $h0 killed $h0 killed $q0
+; NOFP16-NEXT: ret
+;
+; FP16-LABEL: ct_f16:
+; FP16: // %bb.0:
+; FP16-NEXT: tst w0, #0x1
+; FP16-NEXT: fcsel h0, h0, h1, ne
+; FP16-NEXT: ret
+ %1 = call half @llvm.ct.select.f16(i1 %cond, half %a, half %b)
+ ret half %1
+}
+
+define float @ct_f32(i1 %cond, float %a, float %b) {
+; DEFAULT-LABEL: ct_f32:
+; DEFAULT: // %bb.0:
+; DEFAULT-NEXT: tst w0, #0x1
+; DEFAULT-NEXT: fcsel s0, s0, s1, ne
+; DEFAULT-NEXT: ret
+ %1 = call float @llvm.ct.select.f32(i1 %cond, float %a, float %b)
+ ret float %1
+}
+
+define double @ct_f64(i1 %cond, double %a, double %b) {
+; DEFAULT-LABEL: ct_f64:
+; DEFAULT: // %bb.0:
+; DEFAULT-NEXT: tst w0, #0x1
+; DEFAULT-NEXT: fcsel d0, d0, d1, ne
+; DEFAULT-NEXT: ret
+ %1 = call double @llvm.ct.select.f64(i1 %cond, double %a, double %b)
+ ret double %1
+}
+
+define <4 x i32> @ct_v4i32(i1 %cond, <4 x i32> %a, <4 x i32> %b) {
+; DEFAULT-LABEL: ct_v4i32:
+; DEFAULT: // %bb.0:
+; DEFAULT-NEXT: dup v2.4h, w0
+; DEFAULT-NEXT: eor v0.16b, v0.16b, v1.16b
+; DEFAULT-NEXT: ushll v2.4s, v2.4h, #0
+; DEFAULT-NEXT: shl v2.4s, v2.4s, #31
+; DEFAULT-NEXT: cmlt v2.4s, v2.4s, #0
+; DEFAULT-NEXT: and v0.16b, v0.16b, v2.16b
+; DEFAULT-NEXT: eor v0.16b, v1.16b, v0.16b
+; DEFAULT-NEXT: ret
+ %1 = call <4 x i32> @llvm.ct.select.v4i32(i1 %cond, <4 x i32> %a, <4 x i32> %b)
+ ret <4 x i32> %1
+}
+
+define <4 x float> @ct_v4f32(i1 %cond, <4 x float> %a, <4 x float> %b) {
+; DEFAULT-LABEL: ct_v4f32:
+; DEFAULT: // %bb.0:
+; DEFAULT-NEXT: dup v2.4h, w0
+; DEFAULT-NEXT: eor v0.16b, v0.16b, v1.16b
+; DEFAULT-NEXT: ushll v2.4s, v2.4h, #0
+; DEFAULT-NEXT: shl v2.4s, v2.4s, #31
+; DEFAULT-NEXT: cmlt v2.4s, v2.4s, #0
+; DEFAULT-NEXT: and v0.16b, v0.16b, v2.16b
+; DEFAULT-NEXT: eor v0.16b, v1.16b, v0.16b
+; DEFAULT-NEXT: ret
+ %1 = call <4 x float> @llvm.ct.select.v4f32(i1 %cond, <4 x float> %a, <4 x float> %b)
+ ret <4 x float> %1
+}
>From 845e7ec993c20ed0ad8c675aaee764d7d1987e61 Mon Sep 17 00:00:00 2001
From: wizardengineer <juliuswoosebert at gmail.com>
Date: Fri, 22 May 2026 12:14:56 -0400
Subject: [PATCH 3/3] [AArch64] Regen ctselect.ll for new core legalization
---
llvm/test/CodeGen/AArch64/ctselect.ll | 27 +++++++++------------------
1 file changed, 9 insertions(+), 18 deletions(-)
diff --git a/llvm/test/CodeGen/AArch64/ctselect.ll b/llvm/test/CodeGen/AArch64/ctselect.ll
index 4df452b05af72..d9606e059e76d 100644
--- a/llvm/test/CodeGen/AArch64/ctselect.ll
+++ b/llvm/test/CodeGen/AArch64/ctselect.ll
@@ -67,16 +67,11 @@ define i128 @ct_i128(i1 %cond, i128 %a, i128 %b) {
define half @ct_f16(i1 %cond, half %a, half %b) {
; NOFP16-LABEL: ct_f16:
; NOFP16: // %bb.0:
-; NOFP16-NEXT: // kill: def $h1 killed $h1 def $s1
-; NOFP16-NEXT: // kill: def $h0 killed $h0 def $s0
-; NOFP16-NEXT: fmov w9, s0
-; NOFP16-NEXT: fmov w10, s1
-; NOFP16-NEXT: sbfx w8, w0, #0, #1
-; NOFP16-NEXT: bic w10, w10, w8
-; NOFP16-NEXT: and w8, w9, w8
-; NOFP16-NEXT: orr w8, w8, w10
-; NOFP16-NEXT: fmov s0, w8
-; NOFP16-NEXT: // kill: def $h0 killed $h0 killed $q0
+; NOFP16-NEXT: fcvt s1, h1
+; NOFP16-NEXT: fcvt s0, h0
+; NOFP16-NEXT: tst w0, #0x1
+; NOFP16-NEXT: fcsel s0, s0, s1, ne
+; NOFP16-NEXT: fcvt h0, s0
; NOFP16-NEXT: ret
;
; FP16-LABEL: ct_f16:
@@ -111,11 +106,9 @@ define double @ct_f64(i1 %cond, double %a, double %b) {
define <4 x i32> @ct_v4i32(i1 %cond, <4 x i32> %a, <4 x i32> %b) {
; DEFAULT-LABEL: ct_v4i32:
; DEFAULT: // %bb.0:
-; DEFAULT-NEXT: dup v2.4h, w0
+; DEFAULT-NEXT: sbfx w8, w0, #0, #1
; DEFAULT-NEXT: eor v0.16b, v0.16b, v1.16b
-; DEFAULT-NEXT: ushll v2.4s, v2.4h, #0
-; DEFAULT-NEXT: shl v2.4s, v2.4s, #31
-; DEFAULT-NEXT: cmlt v2.4s, v2.4s, #0
+; DEFAULT-NEXT: dup v2.4s, w8
; DEFAULT-NEXT: and v0.16b, v0.16b, v2.16b
; DEFAULT-NEXT: eor v0.16b, v1.16b, v0.16b
; DEFAULT-NEXT: ret
@@ -126,11 +119,9 @@ define <4 x i32> @ct_v4i32(i1 %cond, <4 x i32> %a, <4 x i32> %b) {
define <4 x float> @ct_v4f32(i1 %cond, <4 x float> %a, <4 x float> %b) {
; DEFAULT-LABEL: ct_v4f32:
; DEFAULT: // %bb.0:
-; DEFAULT-NEXT: dup v2.4h, w0
+; DEFAULT-NEXT: sbfx w8, w0, #0, #1
; DEFAULT-NEXT: eor v0.16b, v0.16b, v1.16b
-; DEFAULT-NEXT: ushll v2.4s, v2.4h, #0
-; DEFAULT-NEXT: shl v2.4s, v2.4s, #31
-; DEFAULT-NEXT: cmlt v2.4s, v2.4s, #0
+; DEFAULT-NEXT: dup v2.4s, w8
; DEFAULT-NEXT: and v0.16b, v0.16b, v2.16b
; DEFAULT-NEXT: eor v0.16b, v1.16b, v0.16b
; DEFAULT-NEXT: ret
More information about the llvm-branch-commits
mailing list