[X86] Skip over DEBUG_VALUE while looking for call sequence

[mkuper]

Summary

This fixes PR31242.

[hans]

lgtm

llvm/trunk/lib/Target/X86/X86CallFrameOptimization.cpp

unsigned int MaxAdjust =
       FrameSetup->getOperand(0).getImm() >> Log2SlotSize;
 
   // A zero adjustment means no stack parameters
   if (!MaxAdjust) {
     Context.NoStackParams = true;
     return;
   }
 
-  // For globals in PIC mode, we can have some LEAs here.
-  // Ignore them, they don't bother us.
+  // Skip over DEBUG_VALUE.
+  // For globals in PIC mode, we can have some LEAs here. Skip them as well.
   // TODO: Extend this to something that covers more cases.
-  while (I->getOpcode() == X86::LEA32r)
+  while (I->getOpcode() == X86::LEA32r || I->isDebugValue())
     ++I;
 
   unsigned StackPtr = RegInfo.getStackRegister();
   // SelectionDAG (but not FastISel) inserts a copy of ESP into a virtual
   // register here.  If it's there, use that virtual register as stack pointer
   // instead.
   if (I->isCopy() && I->getOperand(0).isReg() && I->getOperand(1).isReg() &&
       I->getOperand(1).getReg() == StackPtr) {

llvm/trunk/test/CodeGen/X86/pr31242.ll

+; RUN: llc -mtriple=x86_64-unknown-linux-gnu < %s | FileCheck %s
+
+declare void @raf(i32, ...)
+
+; CHECK-LABEL: test3
+; CHECK-DAG:   movl    $7, %edi
+; CHECK-DAG:   xorl    %esi, %esi
+; CHECK-DAG:   xorl    %edx, %edx
+; CHECK-DAG:   xorl    %ecx, %ecx
+; CHECK-DAG:   xorl    %r8d, %r8d
+; CHECK-DAG:   xorl    %r9d, %r9d
+; CHECK-DAG:   xorl    %eax, %eax
+; CHECK:       pushq   %rbx
+; CHECK:       pushq   $0
+; CHECK:       callq   raf
+
+
+; Function Attrs: nounwind uwtable
+define void @test3() {
+entry:
+  br label %for.body
+
+for.body:
+  %i.04 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  tail call void @llvm.dbg.value(metadata i32 %i.04, i64 0, metadata !10, metadata !12), !dbg !6
+  tail call void (i32, ...) @raf(i32 7, i32 0, i32 0, i32 0, i32 0, i32 0, i32 0, i32 %i.04)
+  %inc = add nuw nsw i32 %i.04, 1
+  %exitcond = icmp eq i32 %inc, 21
+  br i1 %exitcond, label %for.cond.cleanup, label %for.body
+
+for.cond.cleanup:
+  ret void  
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.value(metadata, i64, metadata, metadata) 
+attributes #3 = { nounwind }
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4}
+!llvm.ident = !{!5}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 4.0.0 (trunk 288844)", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "pr31242.c", directory: "")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{!"clang version 4.0.0 (trunk 288844)"}
+!6 = !DILocation(line: 2, column: 16, scope: !7)
+!7 = distinct !DISubprogram(name: "test3", scope: !1, file: !1, line: 5, type: !8, isLocal: false, isDefinition: true, scopeLine: 5, isOptimized: true, unit: !0)
+!8 = !DISubroutineType(types: !9)
+!9 = !{null}
+!10 = !DILocalVariable(name: "value", arg: 1, scope: !7, file: !1, line: 2, type: !11)
+!11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!12 = !DIExpression()