[framelowering] Skip dbg values when getting next/previous instruction.

Summary:
In mergeSPUpdates, debug values need to be ignored when getting the
previous element, otherwise debug data could have an impact on codegen.

In eliminateCallFramePseudoInstr, debug values after the erased element
could have an impact on codegen and should be skipped.

Closes PR31319 (https://llvm.org/bugs/show_bug.cgi?id=31319)

Reviewers: aprantl, MatzeB, mkuper

Subscribers: gbedwell, llvm-commits

Differential Revision: https://reviews.llvm.org/D27688

llvm-svn: 290955

4 files changed, 158 insertions, 16 deletions

diff --git a/llvm/lib/Target/X86/X86FrameLowering.cpp b/llvm/lib/Target/X86/X86FrameLowering.cpp
index 1deefe1231c..cd690442bb9 100644
--- a/llvm/lib/Target/X86/X86FrameLowering.cpp
+++ b/llvm/lib/Target/X86/X86FrameLowering.cpp
@@ -373,6 +373,10 @@ int X86FrameLowering::mergeSPUpdates(MachineBasicBlock &MBB,
   MachineBasicBlock::iterator PI = doMergeWithPrevious ? std::prev(MBBI) : MBBI;
   MachineBasicBlock::iterator NI = doMergeWithPrevious ? nullptr
                                                        : std::next(MBBI);
+  PI = skipDebugInstructionsBackward(PI, MBB.begin());
+  if (NI != nullptr)
+    NI = skipDebugInstructionsForward(NI, MBB.end());
+
   unsigned Opc = PI->getOpcode();
   int Offset = 0;
 
@@ -2586,6 +2590,7 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
   uint64_t Amount = !reserveCallFrame ? I->getOperand(0).getImm() : 0;
   uint64_t InternalAmt = (isDestroy || Amount) ? I->getOperand(1).getImm() : 0;
   I = MBB.erase(I);
+  auto InsertPos = skipDebugInstructionsForward(I, MBB.end());
 
   if (!reserveCallFrame) {
     // If the stack pointer can be changed after prologue, turn the
@@ -2615,7 +2620,7 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
 
     if (HasDwarfEHHandlers && !isDestroy &&
         MF.getInfo<X86MachineFunctionInfo>()->getHasPushSequences())
-      BuildCFI(MBB, I, DL,
+      BuildCFI(MBB, InsertPos, DL,
                MCCFIInstruction::createGnuArgsSize(nullptr, Amount));
 
     if (Amount == 0)
@@ -2629,7 +2634,7 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
     // If this is a callee-pop calling convention, emit a CFA adjust for
     // the amount the callee popped.
     if (isDestroy && InternalAmt && DwarfCFI && !hasFP(MF))
-      BuildCFI(MBB, I, DL, 
+      BuildCFI(MBB, InsertPos, DL,
                MCCFIInstruction::createAdjustCfaOffset(nullptr, -InternalAmt));
 
     // Add Amount to SP to destroy a frame, or subtract to setup.
@@ -2640,13 +2645,13 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
       // Merge with any previous or following adjustment instruction. Note: the
       // instructions merged with here do not have CFI, so their stack
       // adjustments do not feed into CfaAdjustment.
-      StackAdjustment += mergeSPUpdates(MBB, I, true);
-      StackAdjustment += mergeSPUpdates(MBB, I, false);
+      StackAdjustment += mergeSPUpdates(MBB, InsertPos, true);
+      StackAdjustment += mergeSPUpdates(MBB, InsertPos, false);
 
       if (StackAdjustment) {
         if (!(Fn->optForMinSize() &&
-              adjustStackWithPops(MBB, I, DL, StackAdjustment)))
-          BuildStackAdjustment(MBB, I, DL, StackAdjustment,
+              adjustStackWithPops(MBB, InsertPos, DL, StackAdjustment)))
+          BuildStackAdjustment(MBB, InsertPos, DL, StackAdjustment,
                                /*InEpilogue=*/false);
       }
     }
@@ -2662,8 +2667,9 @@ eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
       // TODO: When not using precise CFA, we also need to adjust for the
       // InternalAmt here.
       if (CfaAdjustment) {
-        BuildCFI(MBB, I, DL, MCCFIInstruction::createAdjustCfaOffset(
-                                 nullptr, CfaAdjustment));
+        BuildCFI(MBB, InsertPos, DL,
+                 MCCFIInstruction::createAdjustCfaOffset(nullptr,
+                                                         CfaAdjustment));
       }
     }
 
diff --git a/llvm/test/CodeGen/X86/frame-lowering-debug-intrinsic-2.ll b/llvm/test/CodeGen/X86/frame-lowering-debug-intrinsic-2.ll
new file mode 100644
index 00000000000..ab797e04b40
--- /dev/null
+++ b/llvm/test/CodeGen/X86/frame-lowering-debug-intrinsic-2.ll
@@ -0,0 +1,72 @@
+; Test ensuring debug intrinsics do not affect generated function prologue.
+;
+; RUN: llc -O1 -mtriple=x86_64-unknown-unknown -o - %s | FileCheck %s
+
+@a = local_unnamed_addr global i64 0, align 8
+
+define void @noDebug() {
+entry:
+  %0 = load i64, i64* @a, align 8
+  %1 = load i64, i64* @a, align 8
+  %2 = load i64, i64* @a, align 8
+  %3 = tail call { i64, i1 } @llvm.uadd.with.overflow.i64(i64 %0, i64 %1)
+  %4 = extractvalue { i64, i1 } %3, 0
+  %5 = tail call i64 @fn1(i64 %4, i64 %2)
+  tail call void (...) @printf()
+  tail call void (...) @printf(i64 1, i64 2, i64 3, i64 4, i32 0, i64 0, i64 %4, i64 %5)
+  ret void
+}
+
+; CHECK-LABEL: noDebug
+; CHECK:       addq  $24, %rsp
+; CHECK:       popq  %rbx
+; CHECK-NEXT:  popq  %r14
+; CHECK-NEXT:  retq
+
+
+define void @withDebug() !dbg !18 {
+entry:
+  %0 = load i64, i64* @a, align 8
+  %1 = load i64, i64* @a, align 8
+  %2 = load i64, i64* @a, align 8
+  %3 = tail call { i64, i1 } @llvm.uadd.with.overflow.i64(i64 %0, i64 %1)
+  %4 = extractvalue { i64, i1 } %3, 0
+  %5 = tail call i64 @fn1(i64 %4, i64 %2)
+  tail call void @llvm.dbg.value(metadata i64 %4, i64 0, metadata !23, metadata !33), !dbg !34
+  tail call void @llvm.dbg.value(metadata i64 %5, i64 0, metadata !22, metadata !33), !dbg !35
+  tail call void (...) @printf()
+  tail call void (...) @printf(i64 1, i64 2, i64 3, i64 4, i32 0, i64 0, i64 %4, i64 %5)
+  ret void
+}
+
+; CHECK-LABEL: withDebug
+; CHECK:       #DEBUG_VALUE: test:j <- %RBX
+; CHECK-NEXT:  addq  $24, %rsp
+; CHECK:       popq  %rbx
+; CHECK-NEXT:  popq  %r14
+; CHECK-NEXT:  retq
+
+declare { i64, i1 } @llvm.uadd.with.overflow.i64(i64, i64)
+declare i64 @fn1(i64, i64)
+
+declare void @printf(...)
+
+declare void @llvm.dbg.value(metadata, i64, metadata, metadata)
+
+
+!llvm.dbg.cu = !{!1}
+!llvm.module.flags = !{!15, !16}
+
+!1 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !2, producer: "clang version 4.0.0")
+!2 = !DIFile(filename: "test.cpp", directory: "")
+!11 = !DIBasicType(name: "long int", size: 64, encoding: DW_ATE_signed)
+!15 = !{i32 2, !"Dwarf Version", i32 4}
+!16 = !{i32 2, !"Debug Info Version", i32 3}
+!18 = distinct !DISubprogram(name: "test", scope: !2, file: !2, line: 5, unit: !1)
+!22 = !DILocalVariable(name: "i", scope: !18, file: !2, line: 6, type: !11)
+!23 = !DILocalVariable(name: "j", scope: !18, file: !2, line: 7, type: !11)
+!33 = !DIExpression()
+!34 = !DILocation(line: 7, column: 17, scope: !18)
+!35 = !DILocation(line: 6, column: 8, scope: !18)
+!36 = !DILocation(line: 9, column: 3, scope: !18)
+!37 = !DILocation(line: 10, column: 10, scope: !18)
diff --git a/llvm/test/CodeGen/X86/frame-lowering-debug-intrinsic.ll b/llvm/test/CodeGen/X86/frame-lowering-debug-intrinsic.ll
index 8614d1b4c6c..e86d094ac34 100644
--- a/llvm/test/CodeGen/X86/frame-lowering-debug-intrinsic.ll
+++ b/llvm/test/CodeGen/X86/frame-lowering-debug-intrinsic.ll
@@ -2,31 +2,56 @@
 ;
 ; RUN: llc -O1 -mtriple=x86_64-unknown-unknown -o - %s | FileCheck %s
 
-
-define i64 @noDebug(i64 %a) {
+define i64 @fn1NoDebug(i64 %a) {
   %call = call i64 @fn(i64 %a, i64 0)
   ret i64 %call
 }
 
-; CHECK-LABEL: noDebug
+; CHECK-LABEL: fn1NoDebug
 ; CHECK: popq %rcx
-; CHECK: ret
-
+; CHECK-NEXT: ret
 
-define i64 @withDebug(i64 %a) !dbg !4 {
+define i64 @fn1WithDebug(i64 %a) !dbg !4 {
   %call = call i64 @fn(i64 %a, i64 0)
   tail call void @llvm.dbg.value(metadata i64 %call, i64 0, metadata !5, metadata !6), !dbg !7
   ret i64 %call
 }
 
-; CHECK-LABEL: withDebug
+; CHECK-LABEL: fn1WithDebug
 ; CHECK: popq %rcx
-; CHECK: ret
+; CHECK-NEXT: ret
+
+%struct.Buffer = type { i8, [63 x i8] }
+
+define void @fn2NoDebug(%struct.Buffer* byval align 64 %p1) {
+  ret void
+}
+
+; CHECK-LABEL: fn2NoDebug
+; CHECK: and
+; CHECK-NOT: add
+; CHECK-NOT: sub
+; CHECK: mov
+; CHECK-NEXT: pop
+; CHECK-NEXT: ret
+
+define void @fn2WithDebug(%struct.Buffer* byval align 64 %p1) !dbg !4 {
+  call void @llvm.dbg.declare(metadata %struct.Buffer* %p1, metadata !5, metadata !6), !dbg !7
+  ret void
+}
 
+; CHECK-LABEL: fn2WithDebug
+; CHECK: and
+; CHECK-NOT: add
+; CHECK-NOT: sub
+; CHECK: mov
+; CHECK-NEXT: pop
+; CHECK-NEXT: ret
 
 declare i64 @fn(i64, i64)
 
 declare void @llvm.dbg.value(metadata, i64, metadata, metadata)
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
 
 !llvm.dbg.cu = !{!0}
 !llvm.module.flags = !{!2,!3}
diff --git a/llvm/test/DebugInfo/X86/dbg-value-frame-index.ll b/llvm/test/DebugInfo/X86/dbg-value-frame-index.ll
new file mode 100644
index 00000000000..7b49aacfaef
--- /dev/null
+++ b/llvm/test/DebugInfo/X86/dbg-value-frame-index.ll
@@ -0,0 +1,39 @@
+; RUN: llc -mtriple=x86_64-unknown-unknown -o - %s | FileCheck %s
+
+define i1 @test() !dbg !4 {
+entry:
+  %end = alloca i64, align 8
+  br label %while.cond
+
+while.cond:
+  call void @llvm.dbg.value(metadata i64* %end, i64 0, metadata !5, metadata !6), !dbg !7
+  %call = call i1 @fn(i64* %end, i64* %end, i64* null, i8* null, i64 0, i64* null, i32* null, i8* null), !dbg !7
+  br label %while.body
+
+while.body:
+  br i1 0, label %while.end, label %while.cond
+
+while.end:
+  ret i1 true
+}
+
+; CHECK-LABEL: test
+; CHECK:       #DEBUG_VALUE: test:w <- [%RSP+8]
+
+declare i1 @fn(i64*, i64*, i64*, i8*, i64, i64*, i32*, i8*)
+declare void @llvm.dbg.value(metadata, i64, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!2,!3}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, file: !1, producer: "clang version 4.0.0", emissionKind: FullDebug)
+!1 = !DIFile(filename: "test.c", directory: "/")
+!2 = !{i32 2, !"Dwarf Version", i32 4}
+!3 = !{i32 2, !"Debug Info Version", i32 3}
+!4 = distinct !DISubprogram(name: "test", type: !10, unit: !0)
+!5 = !DILocalVariable(name: "w", scope: !4, type: !9)
+!6 = !DIExpression(DW_OP_deref)
+!7 = !DILocation(line: 210, column: 12, scope: !4)
+!8 = !{!9}
+!9 = !DIBasicType(name: "bool", size: 8, encoding: DW_ATE_boolean)
+!10 = !DISubroutineType(types: !8)