[clang] add no-op __builtin_static_analysis_assume

clang/include/clang/Basic/Builtins.td

@@ -5253,3 +5253,9 @@ def CountedByRef : Builtin {
   let Attributes = [NoThrow, CustomTypeChecking];
   let Prototype = "int(...)";
 }
+
+def StaticAnalysisAssume : Builtin {
+  let Spellings = ["__builtin_static_analysis_assume"];
+  let Attributes = [NoThrow, Const, Pure, UnevaluatedArguments];
+  let Prototype = "void(bool)";
+}

clang/lib/CodeGen/CGBuiltin.cpp

@@ -3733,6 +3733,8 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
 
     return RValue::get(Result);
   }
+  case Builtin::BI__builtin_static_analysis_assume:
+    return RValue::get(nullptr);
   case Builtin::BI__builtin_prefetch: {
     Value *Locality, *RW, *Address = EmitScalarExpr(E->getArg(0));
     // FIXME: Technically these constants should of type 'int', yes?

clang/test/AST/builtin-static-analysis-assume.c

@@ -0,0 +1,22 @@
+// RUN: %clang_cc1 -ast-dump -triple x86_64-linux-gnu %s \
+// RUN: | FileCheck %s --strict-whitespace --check-prefixes=CHECK
+//
+// Tests with serialization:
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-pch -o %t %s
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -include-pch %t -ast-dump-all /dev/null \
+// RUN: | FileCheck %s --strict-whitespace
+
+int fun() {
+    int x = 0;
+    __builtin_static_analysis_assume(++x >= 1);
+    return x;
+}
+
+// CHECK: |-CallExpr {{.*}} <line:11:5, col:46> 'void'
+// CHECK: | |-ImplicitCastExpr {{.*}} <col:5> 'void (*)(_Bool)' <BuiltinFnToFnPtr>
+// CHECK: | | `-DeclRefExpr {{.*}} <col:5> '<builtin fn type>' Function {{.*}} '__builtin_static_analysis_assume' 'void (_Bool)'
+// CHECK: | `-ImplicitCastExpr {{.*}} <col:38, col:45> '_Bool' <IntegralToBoolean>
+// CHECK: |   `-BinaryOperator {{.*}} <col:38, col:45> 'int' '>='
+// CHECK: |     |-UnaryOperator {{.*}} <col:38, col:40> 'int' prefix '++'
+// CHECK: |     | `-DeclRefExpr {{.*}} <col:40> 'int' lvalue Var {{.*}} 'x' 'int'
+// CHECK: |     `-IntegerLiteral {{.*}} <col:45> 'int' 1

clang/test/CodeGen/builtin-static-analysis-assume.c

@@ -0,0 +1,17 @@
+// NOTE: Assertions have been autogenerated by utils/update_cc_test_checks.py UTC_ARGS: --version 6
+// RUN: %clang_cc1 -triple x86_64-linux-gnu -emit-llvm -o - %s \
+// RUN: | FileCheck --check-prefix CHECK %s
+
+// CHECK-LABEL: define dso_local i32 @fun(
+// CHECK-SAME: ) #[[ATTR0:[0-9]+]] {
+// CHECK-NEXT:  [[ENTRY:.*:]]
+// CHECK-NEXT:    [[X:%.*]] = alloca i32, align 4
+// CHECK-NEXT:    store i32 0, ptr [[X]], align 4
+// CHECK-NEXT:    [[TMP0:%.*]] = load i32, ptr [[X]], align 4
+// CHECK-NEXT:    ret i32 [[TMP0]]
+//
+int fun() {
+    int x = 0;
+    __builtin_static_analysis_assume(++x >= 1);
+    return x;
+}

clang/test/Sema/builtin-static-analysis-assume.cpp

@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 %s -fsyntax-only -verify -pedantic
+
+void voidfn();
+
+class Foo{};
+
+int fun() {
+    int x = 0;
+    __builtin_static_analysis_assume(true);
+    __builtin_static_analysis_assume(x <= 0);
+    __builtin_static_analysis_assume(voidfn());  // expected-error{{cannot initialize a parameter of type 'bool' with an rvalue of type 'void}}
+    __builtin_static_analysis_assume(Foo());  // expected-error{{no viable conversion from 'Foo' to 'bool'}}
+    return x;
+}