[CIR] Upstream binary assignments and comma (llvm#135115)

This patch adds `VisitBinAssign` and `VisitBinComma` to the ClangIR
`ScalarExprEmitter` to enable assignments and the comma operator.

---------

Co-authored-by: Morris Hafner <[email protected]>

Author: mmha

clang/include/clang/CIR/MissingFeatures.h

@@ -143,6 +143,7 @@ struct MissingFeatures {
   static bool openMP() { return false; }
   static bool emitCheckedInBoundsGEP() { return false; }
   static bool preservedAccessIndexRegion() { return false; }
+  static bool bitfields() { return false; }
 
   // Missing types
   static bool dataMemberType() { return false; }

clang/lib/CIR/CodeGen/CIRGenDecl.cpp

@@ -277,3 +277,11 @@ void CIRGenFunction::emitDecl(const Decl &d) {
     cgm.errorNYI(d.getSourceRange(), "emitDecl: unhandled decl type");
   }
 }
+
+void CIRGenFunction::emitNullabilityCheck(LValue lhs, mlir::Value rhs,
+                                          SourceLocation loc) {
+  if (!sanOpts.has(SanitizerKind::NullabilityAssign))
+    return;
+
+  assert(!cir::MissingFeatures::sanitizers());
+}

clang/lib/CIR/CodeGen/CIRGenExpr.cpp

@@ -257,6 +257,13 @@ void CIRGenFunction::emitStoreOfScalar(mlir::Value value, Address addr,
   assert(!cir::MissingFeatures::opTBAA());
 }
 
+mlir::Value CIRGenFunction::emitStoreThroughBitfieldLValue(RValue src,
+                                                           LValue dst) {
+  assert(!cir::MissingFeatures::bitfields());
+  cgm.errorNYI("bitfields");
+  return {};
+}
+
 mlir::Value CIRGenFunction::emitToMemory(mlir::Value value, QualType ty) {
   // Bool has a different representation in memory than in registers,
   // but in ClangIR, it is simply represented as a cir.bool value.

clang/lib/CIR/CodeGen/CIRGenExprScalar.cpp

@@ -21,6 +21,7 @@
 #include "mlir/IR/Value.h"
 
 #include <cassert>
+#include <utility>
 
 using namespace clang;
 using namespace clang::CIRGen;
@@ -818,6 +819,65 @@ class ScalarExprEmitter : public StmtVisitor<ScalarExprEmitter, mlir::Value> {
   VISITCOMP(EQ)
   VISITCOMP(NE)
 #undef VISITCOMP
+
+  mlir::Value VisitBinAssign(const BinaryOperator *e) {
+    const bool ignore = std::exchange(ignoreResultAssign, false);
+
+    mlir::Value rhs;
+    LValue lhs;
+
+    switch (e->getLHS()->getType().getObjCLifetime()) {
+    case Qualifiers::OCL_Strong:
+    case Qualifiers::OCL_Autoreleasing:
+    case Qualifiers::OCL_ExplicitNone:
+    case Qualifiers::OCL_Weak:
+      assert(!cir::MissingFeatures::objCLifetime());
+      break;
+    case Qualifiers::OCL_None:
+      // __block variables need to have the rhs evaluated first, plus this
+      // should improve codegen just a little.
+      rhs = Visit(e->getRHS());
+      assert(!cir::MissingFeatures::sanitizers());
+      // TODO(cir): This needs to be emitCheckedLValue() once we support
+      // sanitizers
+      lhs = cgf.emitLValue(e->getLHS());
+
+      // Store the value into the LHS. Bit-fields are handled specially because
+      // the result is altered by the store, i.e., [C99 6.5.16p1]
+      // 'An assignment expression has the value of the left operand after the
+      // assignment...'.
+      if (lhs.isBitField()) {
+        rhs = cgf.emitStoreThroughBitfieldLValue(RValue::get(rhs), lhs);
+      } else {
+        cgf.emitNullabilityCheck(lhs, rhs, e->getExprLoc());
+        CIRGenFunction::SourceLocRAIIObject loc{
+            cgf, cgf.getLoc(e->getSourceRange())};
+        cgf.emitStoreThroughLValue(RValue::get(rhs), lhs);
+      }
+    }
+
+    // If the result is clearly ignored, return now.
+    if (ignore)
+      return nullptr;
+
+    // The result of an assignment in C is the assigned r-value.
+    if (!cgf.getLangOpts().CPlusPlus)
+      return rhs;
+
+    // If the lvalue is non-volatile, return the computed value of the
+    // assignment.
+    if (!lhs.isVolatile())
+      return rhs;
+
+    // Otherwise, reload the value.
+    return emitLoadOfLValue(lhs, e->getExprLoc());
+  }
+
+  mlir::Value VisitBinComma(const BinaryOperator *e) {
+    cgf.emitIgnoredExpr(e->getLHS());
+    // NOTE: We don't need to EnsureInsertPoint() like LLVM codegen.
+    return Visit(e->getRHS());
+  }
 };
 
 LValue ScalarExprEmitter::emitCompoundAssignLValue(

clang/lib/CIR/CodeGen/CIRGenFunction.h

@@ -579,6 +579,8 @@ class CIRGenFunction : public CIRGenTypeCache {
   /// is 'Ty'.
   void emitStoreThroughLValue(RValue src, LValue dst, bool isInit = false);
 
+  mlir::Value emitStoreThroughBitfieldLValue(RValue src, LValue dstresult);
+
   /// Given a value and its clang type, returns the value casted to its memory
   /// representation.
   /// Note: CIR defers most of the special casting to the final lowering passes
@@ -593,6 +595,11 @@ class CIRGenFunction : public CIRGenTypeCache {
 
   mlir::LogicalResult emitWhileStmt(const clang::WhileStmt &s);
 
+  /// Given an assignment `*lhs = rhs`, emit a test that checks if \p rhs is
+  /// nonnull, if 1\p LHS is marked _Nonnull.
+  void emitNullabilityCheck(LValue lhs, mlir::Value rhs,
+                            clang::SourceLocation loc);
+
   /// ----------------------
   /// CIR build helpers
   /// -----------------

clang/test/CIR/CodeGen/binassign.c

@@ -0,0 +1,56 @@
+// RUN: %clang_cc1 -std=c23 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck --input-file=%t.cir %s -check-prefix=CIR
+// RUN: %clang_cc1 -std=c23 -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=c23 -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
+
+void binary_assign(void) {
+    bool b;
+    char c;
+    float f;
+    int i;
+
+    b = true;
+    c = 65;
+    f = 3.14f;
+    i = 42;
+}
+
+// CIR-LABEL: cir.func @binary_assign() {
+// CIR:         %[[B:.*]] = cir.alloca !cir.bool, !cir.ptr<!cir.bool>, ["b"]
+// CIR:         %[[C:.*]] = cir.alloca !s8i, !cir.ptr<!s8i>, ["c"]
+// CIR:         %[[F:.*]] = cir.alloca !cir.float, !cir.ptr<!cir.float>, ["f"]
+// CIR:         %[[I:.*]] = cir.alloca !s32i, !cir.ptr<!s32i>, ["i"]
+// CIR:         %[[TRUE:.*]] = cir.const #true
+// CIR:         cir.store %[[TRUE]], %[[B]] : !cir.bool, !cir.ptr<!cir.bool>
+// CIR:         %[[CHAR_INI_INIT:.*]] = cir.const #cir.int<65> : !s32i
+// CIR:         %[[CHAR_VAL:.*]] = cir.cast(integral, %[[CHAR_INI_INIT]] : !s32i), !s8i
+// CIR:         cir.store %[[CHAR_VAL]], %[[C]] : !s8i, !cir.ptr<!s8i>
+// CIR:         %[[FLOAT_VAL:.*]] = cir.const #cir.fp<3.140000e+00> : !cir.float
+// CIR:         cir.store %[[FLOAT_VAL]], %[[F]] : !cir.float, !cir.ptr<!cir.float>
+// CIR:         %[[INT_VAL:.*]] = cir.const #cir.int<42> : !s32i
+// CIR:         cir.store %[[INT_VAL]], %[[I]] : !s32i, !cir.ptr<!s32i>
+// CIR:         cir.return
+
+// LLVM-LABEL: define {{.*}}void @binary_assign() {
+// LLVM:         %[[B_PTR:.*]] = alloca i8
+// LLVM:         %[[C_PTR:.*]] = alloca i8
+// LLVM:         %[[F_PTR:.*]] = alloca float
+// LLVM:         %[[I_PTR:.*]] = alloca i32
+// LLVM:         store i8 1, ptr %[[B_PTR]]
+// LLVM:         store i8 65, ptr %[[C_PTR]]
+// LLVM:         store float 0x40091EB860000000, ptr %[[F_PTR]]
+// LLVM:         store i32 42, ptr %[[I_PTR]]
+// LLVM:         ret void
+
+// OGCG-LABEL: define {{.*}}void @binary_assign()
+// OGCG:         %[[B_PTR:.*]] = alloca i8
+// OGCG:         %[[C_PTR:.*]] = alloca i8
+// OGCG:         %[[F_PTR:.*]] = alloca float
+// OGCG:         %[[I_PTR:.*]] = alloca i32
+// OGCG:         store i8 1, ptr %[[B_PTR]]
+// OGCG:         store i8 65, ptr %[[C_PTR]]
+// OGCG:         store float 0x40091EB860000000, ptr %[[F_PTR]]
+// OGCG:         store i32 42, ptr %[[I_PTR]]
+// OGCG:         ret void

clang/test/CIR/CodeGen/comma.c

@@ -0,0 +1,59 @@
+// RUN: %clang_cc1 -std=c23 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir
+// RUN: FileCheck --input-file=%t.cir %s -check-prefix=CIR
+// RUN: %clang_cc1 -std=c23 -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=c23 -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
+
+void comma(void) {
+    bool b;
+    char c;
+    float f;
+    int i;
+
+    b = true, c = 65, f = 3.14f, i = 42;
+
+    i = 100, 200;
+}
+
+// CIR-LABEL: cir.func @comma() {
+// CIR:         %[[B:.*]] = cir.alloca !cir.bool, !cir.ptr<!cir.bool>, ["b"]
+// CIR:         %[[C:.*]] = cir.alloca !s8i, !cir.ptr<!s8i>, ["c"]
+// CIR:         %[[F:.*]] = cir.alloca !cir.float, !cir.ptr<!cir.float>, ["f"]
+// CIR:         %[[I:.*]] = cir.alloca !s32i, !cir.ptr<!s32i>, ["i"]
+// CIR:         %[[TRUE:.*]] = cir.const #true
+// CIR:         cir.store %[[TRUE]], %[[B]] : !cir.bool, !cir.ptr<!cir.bool>
+// CIR:         %[[CHAR_INI_INIT:.*]] = cir.const #cir.int<65> : !s32i
+// CIR:         %[[CHAR_VAL:.*]] = cir.cast(integral, %[[CHAR_INI_INIT]] : !s32i), !s8i
+// CIR:         cir.store %[[CHAR_VAL]], %[[C]] : !s8i, !cir.ptr<!s8i>
+// CIR:         %[[FLOAT_VAL:.*]] = cir.const #cir.fp<3.140000e+00> : !cir.float
+// CIR:         cir.store %[[FLOAT_VAL]], %[[F]] : !cir.float, !cir.ptr<!cir.float>
+// CIR:         %[[INT_VAL:.*]] = cir.const #cir.int<42> : !s32i
+// CIR:         cir.store %[[INT_VAL]], %[[I]] : !s32i, !cir.ptr<!s32i>
+// CIR:         %[[HUNDRED:.*]] = cir.const #cir.int<100> : !s32i
+// CIR:         cir.store %[[HUNDRED]], %[[I]] : !s32i, !cir.ptr<!s32i>
+// CIR:         cir.return
+
+// LLVM-LABEL: define {{.*}}void @comma() {
+// LLVM:         %[[B_PTR:.*]] = alloca i8
+// LLVM:         %[[C_PTR:.*]] = alloca i8
+// LLVM:         %[[F_PTR:.*]] = alloca float
+// LLVM:         %[[I_PTR:.*]] = alloca i32
+// LLVM:         store i8 1, ptr %[[B_PTR]]
+// LLVM:         store i8 65, ptr %[[C_PTR]]
+// LLVM:         store float 0x40091EB860000000, ptr %[[F_PTR]]
+// LLVM:         store i32 42, ptr %[[I_PTR]]
+// LLVM:         store i32 100, ptr %[[I_PTR]]
+// LLVM:         ret void
+
+// OGCG-LABEL: define {{.*}}void @comma()
+// OGCG:         %[[B_PTR:.*]] = alloca i8
+// OGCG:         %[[C_PTR:.*]] = alloca i8
+// OGCG:         %[[F_PTR:.*]] = alloca float
+// OGCG:         %[[I_PTR:.*]] = alloca i32
+// OGCG:         store i8 1, ptr %[[B_PTR]]
+// OGCG:         store i8 65, ptr %[[C_PTR]]
+// OGCG:         store float 0x40091EB860000000, ptr %[[F_PTR]]
+// OGCG:         store i32 42, ptr %[[I_PTR]]
+// OGCG:         store i32 100, ptr %[[I_PTR]]
+// OGCG:         ret void

clang/test/CIR/IR/binassign.cir

@@ -0,0 +1,45 @@
+// RUN: cir-opt %s | cir-opt | FileCheck %s
+
+!s32i = !cir.int<s, 32>
+!s8i = !cir.int<s, 8>
+#true = #cir.bool<true> : !cir.bool
+module {
+  cir.func @binary_assign() {
+    %0 = cir.alloca !cir.bool, !cir.ptr<!cir.bool>, ["b"] {alignment = 1 : i64}
+    %1 = cir.alloca !s8i, !cir.ptr<!s8i>, ["c"] {alignment = 1 : i64}
+    %2 = cir.alloca !cir.float, !cir.ptr<!cir.float>, ["f"] {alignment = 4 : i64}
+    %3 = cir.alloca !s32i, !cir.ptr<!s32i>, ["i"] {alignment = 4 : i64}
+    %4 = cir.const #true
+    cir.store %4, %0 : !cir.bool, !cir.ptr<!cir.bool>
+    %5 = cir.const #cir.int<65> : !s32i
+    %6 = cir.cast(integral, %5 : !s32i), !s8i
+    cir.store %6, %1 : !s8i, !cir.ptr<!s8i>
+    %7 = cir.const #cir.fp<3.140000e+00> : !cir.float
+    cir.store %7, %2 : !cir.float, !cir.ptr<!cir.float>
+    %8 = cir.const #cir.int<42> : !s32i
+    cir.store %8, %3 : !s32i, !cir.ptr<!s32i>
+    cir.return
+  }
+}
+
+// CHECK: !s32i = !cir.int<s, 32>
+// CHECK: !s8i = !cir.int<s, 8>
+// CHECK: #true = #cir.bool<true> : !cir.bool
+// CHECK: module {
+// CHECK:   cir.func @binary_assign() {
+// CHECK:     %0 = cir.alloca !cir.bool, !cir.ptr<!cir.bool>, ["b"] {alignment = 1 : i64}
+// CHECK:     %1 = cir.alloca !s8i, !cir.ptr<!s8i>, ["c"] {alignment = 1 : i64}
+// CHECK:     %2 = cir.alloca !cir.float, !cir.ptr<!cir.float>, ["f"] {alignment = 4 : i64}
+// CHECK:     %3 = cir.alloca !s32i, !cir.ptr<!s32i>, ["i"] {alignment = 4 : i64}
+// CHECK:     %4 = cir.const #true
+// CHECK:     cir.store %4, %0 : !cir.bool, !cir.ptr<!cir.bool>
+// CHECK:     %5 = cir.const #cir.int<65> : !s32i
+// CHECK:     %6 = cir.cast(integral, %5 : !s32i), !s8i
+// CHECK:     cir.store %6, %1 : !s8i, !cir.ptr<!s8i>
+// CHECK:     %7 = cir.const #cir.fp<3.140000e+00> : !cir.float
+// CHECK:     cir.store %7, %2 : !cir.float, !cir.ptr<!cir.float>
+// CHECK:     %8 = cir.const #cir.int<42> : !s32i
+// CHECK:     cir.store %8, %3 : !s32i, !cir.ptr<!s32i>
+// CHECK:     cir.return
+// CHECK:   }
+// CHECK: }