[CIR] Add Support For Library Builtins (#143984)

This patch upstreams support for builtins that map to a standard library
function. Examples would be abort() and printf().

It also fixes a minor issue with the errorNYI for all remaining
unimplemented builtins using the mlir::Location instead of the clang AST
SourceLocation.

clang/include/clang/CIR/MissingFeatures.h

@@ -236,6 +236,7 @@ struct MissingFeatures {
   static bool runCleanupsScope() { return false; }
   static bool lowerAggregateLoadStore() { return false; }
   static bool dataLayoutTypeAllocSize() { return false; }
+  static bool asmLabelAttr() { return false; }
 
   // Missing types
   static bool dataMemberType() { return false; }

clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp

@@ -20,10 +20,18 @@
 #include "mlir/Support/LLVM.h"
 #include "clang/AST/Expr.h"
 #include "clang/AST/GlobalDecl.h"
+#include "clang/CIR/MissingFeatures.h"
 #include "llvm/Support/ErrorHandling.h"
 
 using namespace clang;
 using namespace clang::CIRGen;
+using namespace llvm;
+
+static RValue emitLibraryCall(CIRGenFunction &cgf, const FunctionDecl *fd,
+                              const CallExpr *e, mlir::Operation *calleeValue) {
+  CIRGenCallee callee = CIRGenCallee::forDirect(calleeValue, GlobalDecl(fd));
+  return cgf.emitCall(e->getCallee()->getType(), callee, e, ReturnValueSlot());
+}
 
 RValue CIRGenFunction::emitBuiltinExpr(const GlobalDecl &gd, unsigned builtinID,
                                        const CallExpr *e,
@@ -49,7 +57,34 @@ RValue CIRGenFunction::emitBuiltinExpr(const GlobalDecl &gd, unsigned builtinID,
     }
   }
 
-  mlir::Location loc = getLoc(e->getExprLoc());
-  cgm.errorNYI(loc, "non constant foldable builtin calls");
+  const FunctionDecl *fd = gd.getDecl()->getAsFunction();
+
+  // If this is an alias for a lib function (e.g. __builtin_sin), emit
+  // the call using the normal call path, but using the unmangled
+  // version of the function name.
+  if (getContext().BuiltinInfo.isLibFunction(builtinID))
+    return emitLibraryCall(*this, fd, e,
+                           cgm.getBuiltinLibFunction(fd, builtinID));
+
+  cgm.errorNYI(e->getSourceRange(), "unimplemented builtin call");
   return getUndefRValue(e->getType());
 }
+
+/// Given a builtin id for a function like "__builtin_fabsf", return a Function*
+/// for "fabsf".
+cir::FuncOp CIRGenModule::getBuiltinLibFunction(const FunctionDecl *fd,
+                                                unsigned builtinID) {
+  assert(astContext.BuiltinInfo.isLibFunction(builtinID));
+
+  // Get the name, skip over the __builtin_ prefix (if necessary). We may have
+  // to build this up so provide a small stack buffer to handle the vast
+  // majority of names.
+  llvm::SmallString<64> name;
+
+  assert(!cir::MissingFeatures::asmLabelAttr());
+  name = astContext.BuiltinInfo.getName(builtinID).substr(10);
+
+  GlobalDecl d(fd);
+  mlir::Type type = convertType(fd->getType());
+  return getOrCreateCIRFunction(name, type, d, /*forVTable=*/false);
+}

clang/lib/CIR/CodeGen/CIRGenModule.h

@@ -301,6 +301,10 @@ public:
                                 cir::FuncType funcType,
                                 const clang::FunctionDecl *funcDecl);
 
+  /// Given a builtin id for a function like "__builtin_fabsf", return a
+  /// Function* for "fabsf".
+  cir::FuncOp getBuiltinLibFunction(const FunctionDecl *fd, unsigned builtinID);
+
   mlir::IntegerAttr getSize(CharUnits size) {
     return builder.getSizeFromCharUnits(size);
   }

clang/test/CIR/CodeGen/builtin_call.cpp

@@ -76,3 +76,21 @@ float constant_fp_builtin_single() {
 // OGCG: define {{.*}}float @_Z26constant_fp_builtin_singlev()
 // OGCG: ret float 0x3FB99999A0000000
 // OGCG: }
+
+void library_builtins() {
+  __builtin_printf(nullptr);
+  __builtin_abort();
+}
+
+// CIR: cir.func @_Z16library_builtinsv() {
+// CIR: %[[NULL:.+]] = cir.const #cir.ptr<null> : !cir.ptr<!s8i>
+// CIR: cir.call @printf(%[[NULL]]) : (!cir.ptr<!s8i>) -> !s32i
+// CIR: cir.call @abort() : () -> ()
+
+// LLVM: define void @_Z16library_builtinsv()
+// LLVM: call i32 (ptr, ...) @printf(ptr null)
+// LLVM: call void @abort()
+
+// OGCG: define dso_local void @_Z16library_builtinsv()
+// OGCG: call i32 (ptr, ...) @printf(ptr noundef null)
+// OGCG: call void @abort()

clang/test/CIR/CodeGen/builtin_printf.cpp

@@ -0,0 +1,65 @@
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-linux-gnu -Wno-unused-value -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck --input-file=%t.cir %s -check-prefix=CIR
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-linux-gnu -Wno-unused-value -fclangir -emit-llvm %s -o %t-cir.ll
+// RUN: FileCheck --input-file=%t-cir.ll %s -check-prefix=LLVM
+// RUN: %clang_cc1 -std=c++11 -triple x86_64-unknown-linux-gnu -Wno-unused-value -emit-llvm %s -o %t.ll
+// RUN: FileCheck --input-file=%t.ll %s -check-prefix=OGCG
+
+// CIR: cir.global "private" cir_private dsolocal @".str" = #cir.const_array<"%s\00" : !cir.array<!s8i x 3>> : !cir.array<!s8i x 3> 
+// CIR: cir.global "private" cir_private dsolocal @".str.1" = #cir.const_array<"%s %d\0A\00" : !cir.array<!s8i x 7>> : !cir.array<!s8i x 7>
+// LLVM: @.str = private global [3 x i8] c"%s\00"
+// LLVM: @.str.1 = private global [7 x i8] c"%s %d\0A\00"
+// OGCG: @.str = private unnamed_addr constant [3 x i8] c"%s\00"
+// OGCG: @.str.1 = private unnamed_addr constant [7 x i8] c"%s %d\0A\00"
+
+void func(char const * const str, int i) {
+  __builtin_printf(nullptr);
+  __builtin_printf("%s", str);
+  __builtin_printf("%s %d\n", str, i);
+}
+
+// CIR: cir.func @printf(!cir.ptr<!s8i>, ...) -> !s32i
+
+// CIR: cir.func @_Z4funcPKci(%[[arg0:.+]]: !cir.ptr<!s8i>{{.*}}, %[[arg1:.+]]: !s32i{{.*}}) {
+// CIR:   %[[str_ptr:.+]] = cir.alloca !cir.ptr<!s8i>, !cir.ptr<!cir.ptr<!s8i>>, ["str", init, const]
+// CIR:   %[[i_ptr:.+]] = cir.alloca !s32i, !cir.ptr<!s32i>, ["i", init]
+// CIR:   cir.store %[[arg0]], %[[str_ptr]] : !cir.ptr<!s8i>, !cir.ptr<!cir.ptr<!s8i>>
+// CIR:   cir.store %[[arg1]], %[[i_ptr]] : !s32i, !cir.ptr<!s32i>
+// CIR:   %[[null_ptr:.+]] = cir.const #cir.ptr<null> : !cir.ptr<!s8i>
+// CIR:   %[[printf_result1:.+]] = cir.call @printf(%[[null_ptr]]) : (!cir.ptr<!s8i>) -> !s32i
+// CIR:   %[[str_fmt_global:.+]] = cir.get_global @".str" : !cir.ptr<!cir.array<!s8i x 3>>
+// CIR:   %[[str_fmt_ptr:.+]] = cir.cast(array_to_ptrdecay, %[[str_fmt_global]] : !cir.ptr<!cir.array<!s8i x 3>>), !cir.ptr<!s8i>
+// CIR:   %[[str_val:.+]] = cir.load{{.*}} %[[str_ptr]] : !cir.ptr<!cir.ptr<!s8i>>, !cir.ptr<!s8i>
+// CIR:   %[[printf_result2:.+]] = cir.call @printf(%[[str_fmt_ptr]], %[[str_val]]) : (!cir.ptr<!s8i>, !cir.ptr<!s8i>) -> !s32i
+// CIR:   %[[full_fmt_global:.+]] = cir.get_global @".str.1" : !cir.ptr<!cir.array<!s8i x 7>>
+// CIR:   %[[full_fmt_ptr:.+]] = cir.cast(array_to_ptrdecay, %[[full_fmt_global]] : !cir.ptr<!cir.array<!s8i x 7>>), !cir.ptr<!s8i>
+// CIR:   %[[str_val2:.+]] = cir.load{{.*}} %[[str_ptr]] : !cir.ptr<!cir.ptr<!s8i>>, !cir.ptr<!s8i>
+// CIR:   %[[i_val:.+]] = cir.load{{.*}} %[[i_ptr]] : !cir.ptr<!s32i>, !s32i
+// CIR:   %[[printf_result3:.+]] = cir.call @printf(%[[full_fmt_ptr]], %[[str_val2]], %[[i_val]]) : (!cir.ptr<!s8i>, !cir.ptr<!s8i>, !s32i) -> !s32i
+// CIR:   cir.return
+
+// LLVM: define void @_Z4funcPKci(ptr %[[arg0:.+]], i32 %[[arg1:.+]])
+// LLVM:   %[[str_ptr:.+]] = alloca ptr
+// LLVM:   %[[i_ptr:.+]] = alloca i32
+// LLVM:   store ptr %[[arg0]], ptr %[[str_ptr]]{{.*}}
+// LLVM:   store i32 %[[arg1]], ptr %[[i_ptr]]{{.*}}
+// LLVM:   %[[printf_result1:.+]] = call i32 (ptr, ...) @printf(ptr null)
+// LLVM:   %[[str_val:.+]] = load ptr, ptr %[[str_ptr]]{{.*}}
+// LLVM:   %[[printf_result2:.+]] = call i32 (ptr, ...) @printf(ptr @.str, ptr %[[str_val]])
+// LLVM:   %[[str_val2:.+]] = load ptr, ptr %[[str_ptr]]{{.*}}
+// LLVM:   %[[i_val:.+]] = load i32, ptr %[[i_ptr]]{{.*}}
+// LLVM:   %[[printf_result3:.+]] = call i32 (ptr, ...) @printf(ptr @.str.1, ptr %[[str_val2]], i32 %[[i_val]])
+// LLVM:   ret void
+
+// OGCG: define dso_local void @_Z4funcPKci(ptr noundef %[[arg0:.+]], i32 noundef %[[arg1:.+]])
+// OGCG:   %[[str_ptr:.+]] = alloca ptr
+// OGCG:   %[[i_ptr:.+]] = alloca i32
+// OGCG:   store ptr %[[arg0]], ptr %[[str_ptr]]{{.*}}
+// OGCG:   store i32 %[[arg1]], ptr %[[i_ptr]]{{.*}}
+// OGCG:   %[[printf_result1:.+]] = call i32 (ptr, ...) @printf(ptr noundef null)
+// OGCG:   %[[str_val:.+]] = load ptr, ptr %[[str_ptr]]{{.*}}
+// OGCG:   %[[printf_result2:.+]] = call i32 (ptr, ...) @printf(ptr noundef @.str, ptr noundef %[[str_val]])
+// OGCG:   %[[str_val2:.+]] = load ptr, ptr %[[str_ptr]]{{.*}}
+// OGCG:   %[[i_val:.+]] = load i32, ptr %[[i_ptr]]{{.*}}
+// OGCG:   %[[printf_result3:.+]] = call i32 (ptr, ...) @printf(ptr noundef @.str.1, ptr noundef %[[str_val2]], i32 noundef %[[i_val]])
+// OGCG:   ret void