GlobalISel: support debug intrinsics.

The translation scheme is mostly cribbed from FastISel, and it's not entirely
convincing semantically. But it does seem to work in the common cases and allow
variables to be printed so it can't be all wrong.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@293228 91177308-0d34-0410-b5e6-96231b3b80d8
(cherry picked from commit ac8bbff)

Author: TNorthover

include/llvm/CodeGen/GlobalISel/MachineIRBuilder.h

@@ -108,6 +108,9 @@ class MachineIRBuilder {
   /// Set the debug location to \p DL for all the next build instructions.
   void setDebugLoc(const DebugLoc &DL) { this->DL = DL; }
 
+  /// Get the current instruction's debug location.
+  DebugLoc getDebugLoc() { return DL; }
+
   /// Build and insert <empty> = \p Opcode <empty>.
   /// The insertion point is the one set by the last call of either
   /// setBasicBlock or setMI.
@@ -127,6 +130,29 @@ class MachineIRBuilder {
   /// Insert an existing instruction at the insertion point.
   MachineInstrBuilder insertInstr(MachineInstrBuilder MIB);
 
+  /// Build and insert a DBG_VALUE instruction expressing the fact that the
+  /// associated \p Variable lives in \p Reg (suitably modified by \p Expr).
+  MachineInstrBuilder buildDirectDbgValue(unsigned Reg, const MDNode *Variable,
+                                          const MDNode *Expr);
+
+  /// Build and insert a DBG_VALUE instruction expressing the fact that the
+  /// associated \p Variable lives in memory at \p Reg + \p Offset (suitably
+  /// modified by \p Expr).
+  MachineInstrBuilder buildIndirectDbgValue(unsigned Reg, unsigned Offset,
+                                            const MDNode *Variable,
+                                            const MDNode *Expr);
+  /// Build and insert a DBG_VALUE instruction expressing the fact that the
+  /// associated \p Variable lives in the stack slot specified by \p FI
+  /// (suitably modified by \p Expr).
+  MachineInstrBuilder buildFIDbgValue(int FI, const MDNode *Variable,
+                                      const MDNode *Expr);
+
+  /// Build and insert a DBG_VALUE instructions specifying that \p Variable is
+  /// given by \p C (suitably modified by \p Expr).
+  MachineInstrBuilder buildConstDbgValue(const Constant &C, unsigned Offset,
+                                         const MDNode *Variable,
+                                         const MDNode *Expr);
+
   /// Build and insert \p Res<def> = G_FRAME_INDEX \p Idx
   ///
   /// G_FRAME_INDEX materializes the address of an alloca value or other

lib/CodeGen/GlobalISel/IRTranslator.cpp

@@ -22,6 +22,7 @@
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/TargetPassConfig.h"
 #include "llvm/IR/Constant.h"
+#include "llvm/IR/DebugInfo.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/GetElementPtrTypeIterator.h"
 #include "llvm/IR/IntrinsicInst.h"
@@ -522,12 +523,60 @@ bool IRTranslator::translateKnownIntrinsic(const CallInst &CI, Intrinsic::ID ID,
   switch (ID) {
   default:
     break;
-  case Intrinsic::dbg_declare:
-  case Intrinsic::dbg_value:
-    // FIXME: these obviously need to be supported properly.
-    if (!TPC->isGlobalISelAbortEnabled())
-      MF->getProperties().set(MachineFunctionProperties::Property::FailedISel);
+  case Intrinsic::dbg_declare: {
+    const DbgDeclareInst &DI = cast<DbgDeclareInst>(CI);
+    assert(DI.getVariable() && "Missing variable");
+
+    const Value *Address = DI.getAddress();
+    if (!Address || isa<UndefValue>(Address)) {
+      DEBUG(dbgs() << "Dropping debug info for " << DI << "\n");
+      return true;
+    }
+
+    unsigned Reg = getOrCreateVReg(*Address);
+    auto RegDef = MRI->def_instr_begin(Reg);
+    assert(DI.getVariable()->isValidLocationForIntrinsic(
+               MIRBuilder.getDebugLoc()) &&
+           "Expected inlined-at fields to agree");
+
+    if (RegDef != MRI->def_instr_end() &&
+        RegDef->getOpcode() == TargetOpcode::G_FRAME_INDEX) {
+      MIRBuilder.buildFIDbgValue(RegDef->getOperand(1).getIndex(),
+                                 DI.getVariable(), DI.getExpression());
+    } else
+      MIRBuilder.buildDirectDbgValue(Reg, DI.getVariable(), DI.getExpression());
+    return true;
+  }
+  case Intrinsic::dbg_value: {
+    // This form of DBG_VALUE is target-independent.
+    const DbgValueInst &DI = cast<DbgValueInst>(CI);
+    const Value *V = DI.getValue();
+    assert(DI.getVariable()->isValidLocationForIntrinsic(
+               MIRBuilder.getDebugLoc()) &&
+           "Expected inlined-at fields to agree");
+    if (!V) {
+      // Currently the optimizer can produce this; insert an undef to
+      // help debugging.  Probably the optimizer should not do this.
+      MIRBuilder.buildIndirectDbgValue(0, DI.getOffset(), DI.getVariable(),
+                                       DI.getExpression());
+    } else if (const auto *CI = dyn_cast<Constant>(V)) {
+      MIRBuilder.buildConstDbgValue(*CI, DI.getOffset(), DI.getVariable(),
+                                    DI.getExpression());
+    } else {
+      unsigned Reg = getOrCreateVReg(*V);
+      // FIXME: This does not handle register-indirect values at offset 0. The
+      // direct/indirect thing shouldn't really be handled by something as
+      // implicit as reg+noreg vs reg+imm in the first palce, but it seems
+      // pretty baked in right now.
+      if (DI.getOffset() != 0)
+        MIRBuilder.buildIndirectDbgValue(Reg, DI.getOffset(), DI.getVariable(),
+                                         DI.getExpression());
+      else
+        MIRBuilder.buildDirectDbgValue(Reg, DI.getVariable(),
+                                       DI.getExpression());
+    }
     return true;
+  }
   case Intrinsic::uadd_with_overflow:
     return translateOverflowIntrinsic(CI, TargetOpcode::G_UADDE, MIRBuilder);
   case Intrinsic::sadd_with_overflow:

lib/CodeGen/GlobalISel/MachineIRBuilder.cpp

@@ -15,6 +15,7 @@
 #include "llvm/CodeGen/MachineInstr.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/IR/DebugInfo.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/Target/TargetOpcodes.h"
 #include "llvm/Target/TargetSubtargetInfo.h"
@@ -82,6 +83,66 @@ MachineInstrBuilder MachineIRBuilder::insertInstr(MachineInstrBuilder MIB) {
   return MIB;
 }
 
+MachineInstrBuilder MachineIRBuilder::buildDirectDbgValue(
+    unsigned Reg, const MDNode *Variable, const MDNode *Expr) {
+  assert(isa<DILocalVariable>(Variable) && "not a variable");
+  assert(cast<DIExpression>(Expr)->isValid() && "not an expression");
+  assert(cast<DILocalVariable>(Variable)->isValidLocationForIntrinsic(DL) &&
+         "Expected inlined-at fields to agree");
+  return buildInstr(TargetOpcode::DBG_VALUE)
+      .addReg(Reg, RegState::Debug)
+      .addReg(0, RegState::Debug)
+      .addMetadata(Variable)
+      .addMetadata(Expr);
+}
+
+MachineInstrBuilder MachineIRBuilder::buildIndirectDbgValue(
+    unsigned Reg, unsigned Offset, const MDNode *Variable, const MDNode *Expr) {
+  assert(isa<DILocalVariable>(Variable) && "not a variable");
+  assert(cast<DIExpression>(Expr)->isValid() && "not an expression");
+  assert(cast<DILocalVariable>(Variable)->isValidLocationForIntrinsic(DL) &&
+         "Expected inlined-at fields to agree");
+  return buildInstr(TargetOpcode::DBG_VALUE)
+      .addReg(Reg, RegState::Debug)
+      .addImm(Offset)
+      .addMetadata(Variable)
+      .addMetadata(Expr);
+}
+
+MachineInstrBuilder MachineIRBuilder::buildFIDbgValue(int FI,
+                                                      const MDNode *Variable,
+                                                      const MDNode *Expr) {
+  assert(isa<DILocalVariable>(Variable) && "not a variable");
+  assert(cast<DIExpression>(Expr)->isValid() && "not an expression");
+  assert(cast<DILocalVariable>(Variable)->isValidLocationForIntrinsic(DL) &&
+         "Expected inlined-at fields to agree");
+  return buildInstr(TargetOpcode::DBG_VALUE)
+      .addFrameIndex(FI)
+      .addImm(0)
+      .addMetadata(Variable)
+      .addMetadata(Expr);
+}
+
+MachineInstrBuilder MachineIRBuilder::buildConstDbgValue(const Constant &C,
+                                                         unsigned Offset,
+                                                         const MDNode *Variable,
+                                                         const MDNode *Expr) {
+  assert(isa<DILocalVariable>(Variable) && "not a variable");
+  assert(cast<DIExpression>(Expr)->isValid() && "not an expression");
+  assert(cast<DILocalVariable>(Variable)->isValidLocationForIntrinsic(DL) &&
+         "Expected inlined-at fields to agree");
+  auto MIB = buildInstr(TargetOpcode::DBG_VALUE);
+  if (auto *CI = dyn_cast<ConstantInt>(&C)) {
+    if (CI->getBitWidth() > 64)
+      MIB.addCImm(CI);
+    else
+      MIB.addImm(CI->getZExtValue());
+  } else
+    MIB.addFPImm(&cast<ConstantFP>(C));
+
+  return MIB.addImm(Offset).addMetadata(Variable).addMetadata(Expr);
+}
+
 MachineInstrBuilder MachineIRBuilder::buildFrameIndex(unsigned Res, int Idx) {
   assert(MRI->getType(Res).isPointer() && "invalid operand type");
   return buildInstr(TargetOpcode::G_FRAME_INDEX)

test/CodeGen/AArch64/GlobalISel/arm64-fallback.ll

@@ -82,36 +82,3 @@ define void @legal_default(i64 %in) {
   insertvalue [2 x i64] undef, i64 %in, 0
   ret void
 }
-
-; FALLBACK-WITH-REPORT-ERR: warning: Instruction selection used fallback path for debug_insts
-; FALLBACK-WITH-REPORT-LABEL: debug_insts:
-define void @debug_insts(i32 %in) #0 !dbg !7 {
-entry:
-  %in.addr = alloca i32, align 4
-  store i32 %in, i32* %in.addr, align 4
-  call void @llvm.dbg.declare(metadata i32* %in.addr, metadata !11, metadata !12), !dbg !13
-  ret void, !dbg !14
-}
-
-; Function Attrs: nounwind readnone
-declare void @llvm.dbg.declare(metadata, metadata, metadata)
-
-!llvm.dbg.cu = !{!0}
-!llvm.module.flags = !{!3, !4, !5}
-!llvm.ident = !{!6}
-
-!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 4.0.0 (trunk 289075) (llvm/trunk 289080)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
-!1 = !DIFile(filename: "tmp.c", directory: "/Users/tim/llvm/build")
-!2 = !{}
-!3 = !{i32 2, !"Dwarf Version", i32 4}
-!4 = !{i32 2, !"Debug Info Version", i32 3}
-!5 = !{i32 1, !"PIC Level", i32 2}
-!6 = !{!"clang version 4.0.0 (trunk 289075) (llvm/trunk 289080)"}
-!7 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 1, type: !8, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
-!8 = !DISubroutineType(types: !9)
-!9 = !{null, !10}
-!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
-!11 = !DILocalVariable(name: "in", arg: 1, scope: !7, file: !1, line: 1, type: !10)
-!12 = !DIExpression()
-!13 = !DILocation(line: 1, column: 14, scope: !7)
-!14 = !DILocation(line: 2, column: 1, scope: !7)

test/CodeGen/AArch64/GlobalISel/debug-insts.ll

@@ -0,0 +1,51 @@
+; RUN: llc -global-isel -mtriple=aarch64 %s -stop-after=irtranslator -o - | FileCheck %s
+
+
+; CHECK-LABEL: name: debug_declare
+; CHECK: DBG_VALUE %stack.0.in.addr, 0, !11, !12, debug-location !13
+; CHECK: DBG_VALUE debug-use %0(s32), debug-use _, !11, !12, debug-location !13
+define void @debug_declare(i32 %in) #0 !dbg !7 {
+entry:
+  %in.addr = alloca i32, align 4
+  store i32 %in, i32* %in.addr, align 4
+  call void @llvm.dbg.declare(metadata i32* %in.addr, metadata !11, metadata !12), !dbg !13
+  call void @llvm.dbg.declare(metadata i32 %in, metadata !11, metadata !12), !dbg !13
+  ret void, !dbg !14
+}
+
+; CHECK-LABEL: name: debug_value
+; CHECK: [[IN:%[0-9]+]](s32) = COPY %w0
+; CHECK: DBG_VALUE debug-use [[IN]](s32), debug-use _, !11, !12, debug-location !13
+; CHECK: DBG_VALUE debug-use %1(p0), debug-use _, !11, !15, debug-location !13
+define void @debug_value(i32 %in) #0 !dbg !7 {
+  %addr = alloca i32
+  call void @llvm.dbg.value(metadata i32 %in, i64 0, metadata !11, metadata !12), !dbg !13
+  store i32 %in, i32* %addr
+  call void @llvm.dbg.value(metadata i32* %addr, i64 0, metadata !11, metadata !15), !dbg !13
+  ret void
+}
+
+; Function Attrs: nounwind readnone
+declare void @llvm.dbg.declare(metadata, metadata, metadata)
+declare void @llvm.dbg.value(metadata, i64, metadata, metadata)
+
+!llvm.dbg.cu = !{!0}
+!llvm.module.flags = !{!3, !4, !5}
+!llvm.ident = !{!6}
+
+!0 = distinct !DICompileUnit(language: DW_LANG_C99, file: !1, producer: "clang version 4.0.0 (trunk 289075) (llvm/trunk 289080)", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !2)
+!1 = !DIFile(filename: "tmp.c", directory: "/Users/tim/llvm/build")
+!2 = !{}
+!3 = !{i32 2, !"Dwarf Version", i32 4}
+!4 = !{i32 2, !"Debug Info Version", i32 3}
+!5 = !{i32 1, !"PIC Level", i32 2}
+!6 = !{!"clang version 4.0.0 (trunk 289075) (llvm/trunk 289080)"}
+!7 = distinct !DISubprogram(name: "foo", scope: !1, file: !1, line: 1, type: !8, isLocal: false, isDefinition: true, scopeLine: 1, flags: DIFlagPrototyped, isOptimized: false, unit: !0, variables: !2)
+!8 = !DISubroutineType(types: !9)
+!9 = !{null, !10}
+!10 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+!11 = !DILocalVariable(name: "in", arg: 1, scope: !7, file: !1, line: 1, type: !10)
+!12 = !DIExpression()
+!13 = !DILocation(line: 1, column: 14, scope: !7)
+!14 = !DILocation(line: 2, column: 1, scope: !7)
+!15 = !DIExpression(DW_OP_deref)