[CIR][CIRGen] Add support for abs (#1011)

This patch introduces support for the abs family of built-in functions
(abs, labs, llabs).

Author: PikachuHyA

clang/include/clang/CIR/Dialect/IR/CIROps.td

@@ -4121,6 +4121,26 @@ def SinOp : UnaryFPToFPBuiltinOp<"sin", "SinOp">;
 def SqrtOp : UnaryFPToFPBuiltinOp<"sqrt", "SqrtOp">;
 def TruncOp : UnaryFPToFPBuiltinOp<"trunc", "FTruncOp">;
 
+def AbsOp : CIR_Op<"abs", [Pure, SameOperandsAndResultType]> {
+  let arguments = (ins PrimitiveSInt:$src, UnitAttr:$poison);
+  let results = (outs PrimitiveSInt:$result);
+  let summary = [{
+    libc builtin equivalent abs, labs, llabs
+
+    The `poison` argument indicate whether the result value 
+    is a poison value if the first argument is statically or 
+    dynamically an INT_MIN value.
+
+    Example:
+
+    ```mlir
+      %0 = cir.const #cir.int<-42> : s32i
+      %1 = cir.abs %0 poison : s32i
+    ```
+  }];
+  let assemblyFormat = "$src ( `poison` $poison^ )? `:` type($src) attr-dict";
+}
+
 class BinaryFPToFPBuiltinOp<string mnemonic, string llvmOpName>
     : CIR_Op<mnemonic, [Pure, SameOperandsAndResultType]> {
   let summary = [{

clang/lib/CIR/CodeGen/CIRGenBuiltin.cpp

@@ -855,9 +855,33 @@ RValue CIRGenFunction::buildBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
   case Builtin::BIllabs:
   case Builtin::BI__builtin_abs:
   case Builtin::BI__builtin_labs:
-  case Builtin::BI__builtin_llabs:
-    llvm_unreachable("Builtin::BIabs like NYI");
-
+  case Builtin::BI__builtin_llabs: {
+    bool SanitizeOverflow = SanOpts.has(SanitizerKind::SignedIntegerOverflow);
+    auto Arg = buildScalarExpr(E->getArg(0));
+    mlir::Value Result;
+    switch (getLangOpts().getSignedOverflowBehavior()) {
+    case LangOptions::SOB_Defined: {
+      auto Call = getBuilder().create<mlir::cir::AbsOp>(
+          getLoc(E->getExprLoc()), Arg.getType(), Arg, false);
+      Result = Call->getResult(0);
+      break;
+    }
+    case LangOptions::SOB_Undefined: {
+      if (!SanitizeOverflow) {
+        auto Call = getBuilder().create<mlir::cir::AbsOp>(
+            getLoc(E->getExprLoc()), Arg.getType(), Arg, true);
+        Result = Call->getResult(0);
+        break;
+      }
+      llvm_unreachable("BI__builtin_abs with LangOptions::SOB_Undefined when "
+                       "SanitizeOverflow is true");
+    }
+      [[fallthrough]];
+    case LangOptions::SOB_Trapping:
+      llvm_unreachable("BI__builtin_abs with LangOptions::SOB_Trapping");
+    }
+    return RValue::get(Result);
+  }
   case Builtin::BI__builtin_complex: {
     mlir::Value Real = buildScalarExpr(E->getArg(0));
     mlir::Value Imag = buildScalarExpr(E->getArg(1));

clang/lib/CIR/Lowering/DirectToLLVM/LowerToLLVM.cpp

@@ -4155,6 +4155,20 @@ class CIRIsFPClassOpLowering
     return mlir::success();
   }
 };
+class CIRAbsOpLowering : public mlir::OpConversionPattern<mlir::cir::AbsOp> {
+public:
+  using OpConversionPattern<mlir::cir::AbsOp>::OpConversionPattern;
+
+  mlir::LogicalResult
+  matchAndRewrite(mlir::cir::AbsOp op, OpAdaptor adaptor,
+                  mlir::ConversionPatternRewriter &rewriter) const override {
+    auto resTy = this->getTypeConverter()->convertType(op.getType());
+    auto absOp = rewriter.create<mlir::LLVM::AbsOp>(
+        op.getLoc(), resTy, adaptor.getOperands()[0], adaptor.getPoison());
+    rewriter.replaceOp(op, absOp);
+    return mlir::success();
+  }
+};
 
 void populateCIRToLLVMConversionPatterns(
     mlir::RewritePatternSet &patterns, mlir::TypeConverter &converter,
@@ -4193,7 +4207,7 @@ void populateCIRToLLVMConversionPatterns(
       CIREhTypeIdOpLowering, CIRCatchParamOpLowering, CIRResumeOpLowering,
       CIRAllocExceptionOpLowering, CIRFreeExceptionOpLowering,
       CIRThrowOpLowering, CIRIntrinsicCallLowering, CIRBaseClassAddrOpLowering,
-      CIRVTTAddrPointOpLowering, CIRIsFPClassOpLowering
+      CIRVTTAddrPointOpLowering, CIRIsFPClassOpLowering, CIRAbsOpLowering
 #define GET_BUILTIN_LOWERING_LIST
 #include "clang/CIR/Dialect/IR/CIRBuiltinsLowering.inc"
 #undef GET_BUILTIN_LOWERING_LIST

clang/lib/CIR/Lowering/ThroughMLIR/LowerCIRToMLIR.cpp

@@ -46,8 +46,8 @@
 #include "mlir/Transforms/DialectConversion.h"
 #include "clang/CIR/Dialect/IR/CIRDialect.h"
 #include "clang/CIR/Dialect/IR/CIRTypes.h"
-#include "clang/CIR/LoweringHelpers.h"
 #include "clang/CIR/LowerToMLIR.h"
+#include "clang/CIR/LoweringHelpers.h"
 #include "clang/CIR/Passes.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/Sequence.h"
@@ -244,6 +244,17 @@ class CIRFAbsOpLowering : public mlir::OpConversionPattern<mlir::cir::FAbsOp> {
     return mlir::LogicalResult::success();
   }
 };
+class CIRAbsOpLowering : public mlir::OpConversionPattern<mlir::cir::AbsOp> {
+public:
+  using mlir::OpConversionPattern<mlir::cir::AbsOp>::OpConversionPattern;
+
+  mlir::LogicalResult
+  matchAndRewrite(mlir::cir::AbsOp op, OpAdaptor adaptor,
+                  mlir::ConversionPatternRewriter &rewriter) const override {
+    rewriter.replaceOpWithNewOp<mlir::math::AbsIOp>(op, adaptor.getSrc());
+    return mlir::LogicalResult::success();
+  }
+};
 
 class CIRFloorOpLowering
     : public mlir::OpConversionPattern<mlir::cir::FloorOp> {
@@ -1324,12 +1335,12 @@ void populateCIRToMLIRConversionPatterns(mlir::RewritePatternSet &patterns,
       CIRCosOpLowering, CIRGlobalOpLowering, CIRGetGlobalOpLowering,
       CIRCastOpLowering, CIRPtrStrideOpLowering, CIRSqrtOpLowering,
       CIRCeilOpLowering, CIRExp2OpLowering, CIRExpOpLowering, CIRFAbsOpLowering,
-      CIRFloorOpLowering, CIRLog10OpLowering, CIRLog2OpLowering,
-      CIRLogOpLowering, CIRRoundOpLowering, CIRPtrStrideOpLowering,
-      CIRSinOpLowering, CIRShiftOpLowering, CIRBitClzOpLowering,
-      CIRBitCtzOpLowering, CIRBitPopcountOpLowering, CIRBitClrsbOpLowering,
-      CIRBitFfsOpLowering, CIRBitParityOpLowering, CIRIfOpLowering,
-      CIRVectorCreateLowering, CIRVectorInsertLowering,
+      CIRAbsOpLowering, CIRFloorOpLowering, CIRLog10OpLowering,
+      CIRLog2OpLowering, CIRLogOpLowering, CIRRoundOpLowering,
+      CIRPtrStrideOpLowering, CIRSinOpLowering, CIRShiftOpLowering,
+      CIRBitClzOpLowering, CIRBitCtzOpLowering, CIRBitPopcountOpLowering,
+      CIRBitClrsbOpLowering, CIRBitFfsOpLowering, CIRBitParityOpLowering,
+      CIRIfOpLowering, CIRVectorCreateLowering, CIRVectorInsertLowering,
       CIRVectorExtractLowering, CIRVectorCmpOpLowering>(converter,
                                                         patterns.getContext());
 }

clang/test/CIR/CodeGen/libc.c

@@ -1,5 +1,12 @@
 // RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir
 // RUN: FileCheck --input-file=%t.cir %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o %t.ll
+// RUN: FileCheck --check-prefix=LLVM --input-file=%t.ll %s
+
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-cir %s -o %t.cir -fwrapv
+// RUN: FileCheck --check-prefix=CIR_NO_POSION --input-file=%t.cir %s
+// RUN: %clang_cc1 -triple x86_64-unknown-linux-gnu -fclangir -emit-llvm %s -o %t.ll -fwrapv
+// RUN: FileCheck --check-prefix=LLVM_NO_POSION --input-file=%t.ll %s
 
 // Should generate CIR's builtin memcpy op.
 void *memcpy(void *, const void *, unsigned long);
@@ -19,3 +26,30 @@ float testFabsf(float x) {
   return fabsf(x);
   // CHECK: cir.fabs %{{.+}} : !cir.float
 }
+
+int abs(int);
+int testAbs(int x) {
+  return abs(x);
+  // CHECK: cir.abs %{{.+}} poison : !s32i
+  // LLVM: %{{.+}} = call i32 @llvm.abs.i32(i32 %{{.+}}, i1 true)
+  // CIR_NO_POSION: cir.abs %{{.+}} : !s32i
+  // LLVM_NO_POSION: %{{.+}} = call i32 @llvm.abs.i32(i32 %{{.+}}, i1 false)
+}
+
+long labs(long);
+long testLabs(long x) {
+  return labs(x);
+  // CHECK: cir.abs %{{.+}} poison : !s64i
+  // LLVM: %{{.+}} = call i64 @llvm.abs.i64(i64 %{{.+}}, i1 true)
+  // CIR_NO_POSION: cir.abs %{{.+}} : !s64i
+  // LLVM_NO_POSION: %{{.+}} = call i64 @llvm.abs.i64(i64 %{{.+}}, i1 false)
+}
+
+long long llabs(long long);
+long long testLlabs(long long x) {
+  return llabs(x);
+  // CHECK: cir.abs %{{.+}} poison : !s64i
+  // LLVM: %{{.+}} = call i64 @llvm.abs.i64(i64 %{{.+}}, i1 true)
+  // CIR_NO_POSION: cir.abs %{{.+}} : !s64i
+  // LLVM_NO_POSION: %{{.+}} = call i64 @llvm.abs.i64(i64 %{{.+}}, i1 false)
+}

clang/test/CIR/Lowering/ThroughMLIR/abs.cir

@@ -0,0 +1,23 @@
+// RUN: cir-opt %s -cir-to-mlir -o %t.mlir
+// RUN: FileCheck %s --input-file %t.mlir
+!s32i = !cir.int<s, 32>
+!s64i = !cir.int<s, 64>
+module {
+  cir.func @foo() {
+    %0 = cir.const #cir.int<-1> : !s32i
+    %1 = cir.const #cir.int<-2> : !s64i
+    %4 = cir.abs %0 : !s32i
+    %5 = cir.abs %1 : !s64i
+    cir.return
+  }
+}
+
+// CHECK:      module {
+// CHECK-NEXT:   func.func @foo() {
+// CHECK-NEXT:     %[[C0:.+]] = arith.constant -1 : i32
+// CHECK-NEXT:     %[[C1:.+]] = arith.constant -2 : i64
+// CHECK-NEXT:     %{{.+}} = math.absi %[[C0]] : i32
+// CHECK-NEXT:     %{{.+}} = math.absi %[[C1]] : i64
+// CHECK-NEXT:     return
+// CHECK-NEXT:   }
+// CHECK-NEXT: }