[PowerPC] fast isel can lower intrinsics call on AIX.

Reviewed By: qiucf

Differential Revision: https://reviews.llvm.org/D114778

Author: Chen Zheng

llvm/lib/CodeGen/SelectionDAG/FastISel.cpp

@@ -1775,12 +1775,13 @@ bool FastISel::selectOperator(const User *I, unsigned Opcode) {
     return false;
 
   case Instruction::Call:
-    // On AIX, call lowering uses the DAG-ISEL path currently so that the
+    // On AIX, normal call lowering uses the DAG-ISEL path currently so that the
     // callee of the direct function call instruction will be mapped to the
     // symbol for the function's entry point, which is distinct from the
     // function descriptor symbol. The latter is the symbol whose XCOFF symbol
     // name is the C-linkage name of the source level function.
-    if (TM.getTargetTriple().isOSAIX())
+    // But fast isel still has the ability to do selection for intrinsics.
+    if (TM.getTargetTriple().isOSAIX() && !isa<IntrinsicInst>(I))
       return false;
     return selectCall(I);
 

llvm/lib/Target/PowerPC/PPCFastISel.cpp

@@ -1966,15 +1966,6 @@ bool PPCFastISel::fastSelectInstruction(const Instruction *I) {
       return SelectBinaryIntOp(I, ISD::OR);
     case Instruction::Sub:
       return SelectBinaryIntOp(I, ISD::SUB);
-    case Instruction::Call:
-      // On AIX, call lowering uses the DAG-ISEL path currently so that the
-      // callee of the direct function call instruction will be mapped to the
-      // symbol for the function's entry point, which is distinct from the
-      // function descriptor symbol. The latter is the symbol whose XCOFF symbol
-      // name is the C-linkage name of the source level function.
-      if (TM.getTargetTriple().isOSAIX())
-        break;
-      return selectCall(I);
     case Instruction::Ret:
       return SelectRet(I);
     case Instruction::Trunc:

llvm/test/CodeGen/PowerPC/debug-label-fast-isel.ll

@@ -0,0 +1,55 @@
+; RUN: llc < %s -mtriple powerpc64-ibm-aix-xcoff | FileCheck %s --check-prefix=CHECKASM
+
+; This is a case copied from test/DebugInfo/Generic/debug-label-mi.ll. This test
+; is to explicitly check that fast isel for XCOFF works as expected for debug
+; related intrinsics.
+
+; CHECKASM: DEBUG_LABEL: foo:top
+; CHECKASM: DEBUG_LABEL: foo:done
+
+source_filename = "debug-label-mi.c"
+
+; Function Attrs: noinline nounwind optnone
+define i32 @foo(i32 signext %a, i32 signext %b) #0 !dbg !4 {
+entry:
+  %a.addr = alloca i32, align 4
+  %b.addr = alloca i32, align 4
+  %sum = alloca i32, align 4
+  store i32 %a, i32* %a.addr, align 4
+  store i32 %b, i32* %b.addr, align 4
+  br label %top
+
+top:                                              ; preds = %entry
+  call void @llvm.dbg.label(metadata !8), !dbg !9
+  %0 = load i32, i32* %a.addr, align 4
+  %1 = load i32, i32* %b.addr, align 4
+  %add = add nsw i32 %0, %1
+  store i32 %add, i32* %sum, align 4
+  br label %done
+
+done:                                             ; preds = %top
+  call void @llvm.dbg.label(metadata !10), !dbg !11
+  %2 = load i32, i32* %sum, align 4
+  ret i32 %2
+}
+
+; Function Attrs: nounwind readnone speculatable
+declare void @llvm.dbg.label(metadata)
+
+attributes #0 = { noinline nounwind optnone uwtable }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, isOptimized: false, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "debug-label-mi.c", directory: "./")
+!2 = !{}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 1, type: !5, isLocal: false, isDefinition: true, scopeLine: 2, isOptimized: false, unit: !0, retainedNodes: !2)
+!5 = !DISubroutineType(types: !6)
+!6 = !{!7, !7, !7}
+!7 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!8 = !DILabel(scope: !4, name: "top", file: !1, line: 4)
+!9 = !DILocation(line: 4, column: 1, scope: !4)
+!10 = !DILabel(scope: !4, name: "done", file: !1, line: 7)
+!11 = !DILocation(line: 7, column: 1, scope: !4)