IR, CodeGen: Add command line flags for dumping instruction addresses and debug locations.

[pcc]

As previously discussed [1], it is sometimes useful to be able to see
instruction addresses and debug locations as part of IR dumps. The
same applies to MachineInstrs which already dump debug locations but
not addresses. Therefore add some flags that can be used to enable
dumping of this information.

[1] https://discourse.llvm.org/t/small-improvement-to-llvm-debugging-experience/79914

[llvmbot]

@llvm/pr-subscribers-llvm-ir

Author: Peter Collingbourne (pcc)

Changes

As previously discussed [1], it is sometimes useful to be able to see
instruction addresses and debug locations as part of IR dumps. The
same applies to MachineInstrs which already dump debug locations but
not addresses. Therefore add some flags that can be used to enable
dumping of this information.

[1] https://discourse.llvm.org/t/small-improvement-to-llvm-debugging-experience/79914

---

Full diff: https://github.com/llvm/llvm-project/pull/127944.diff

5 Files Affected:

• (modified) llvm/lib/CodeGen/MachineInstr.cpp (+7)
• (modified) llvm/lib/IR/AsmWriter.cpp (+20)
• (added) llvm/test/Other/print-inst-addrs.ll (+6)
• (added) llvm/test/Other/print-inst-debug-locs.ll (+20)
• (added) llvm/test/Other/print-mi-addrs.ll (+11)

diff --git a/llvm/lib/CodeGen/MachineInstr.cpp b/llvm/lib/CodeGen/MachineInstr.cpp
index 52c977a3651a3..6b7e74c04f6d5 100644
--- a/llvm/lib/CodeGen/MachineInstr.cpp
+++ b/llvm/lib/CodeGen/MachineInstr.cpp
@@ -63,6 +63,10 @@
 
 using namespace llvm;
 
+static cl::opt<bool>
+    PrintMIAddrs("print-mi-addrs", cl::Hidden,
+                 cl::desc("Print addresses of MachineInstrs when dumping"));
+
 static const MachineFunction *getMFIfAvailable(const MachineInstr &MI) {
   if (const MachineBasicBlock *MBB = MI.getParent())
     if (const MachineFunction *MF = MBB->getParent())
@@ -2059,6 +2063,9 @@ void MachineInstr::print(raw_ostream &OS, ModuleSlotTracker &MST,
   }
   // TODO: DBG_LABEL
 
+  if (PrintMIAddrs)
+    OS << " ; " << this;
+
   if (AddNewLine)
     OS << '\n';
 }
diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
index 57e9cccdc0fb6..73e6d1c9b0b2f 100644
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -88,6 +88,14 @@
 
 using namespace llvm;
 
+static cl::opt<bool>
+    PrintInstAddrs("print-inst-addrs", cl::Hidden,
+                   cl::desc("Print addresses of instructions when dumping"));
+
+static cl::opt<bool> PrintInstDebugLocs(
+    "print-inst-debug-locs", cl::Hidden,
+    cl::desc("Pretty print debug locations of instructions when dumping"));
+
 // Make virtual table appear in this compilation unit.
 AssemblyAnnotationWriter::~AssemblyAnnotationWriter() = default;
 
@@ -4236,6 +4244,18 @@ void AssemblyWriter::printInfoComment(const Value &V) {
   if (AnnotationWriter) {
     AnnotationWriter->printInfoComment(V, Out);
   }
+
+  if (PrintInstDebugLocs) {
+    if (auto *I = dyn_cast<Instruction>(&V)) {
+      if (I->getDebugLoc()) {
+        Out << " ; ";
+        I->getDebugLoc().print(Out);
+      }
+    }
+  }
+
+  if (PrintInstAddrs)
+    Out << " ; " << &V;
 }
 
 static void maybePrintCallAddrSpace(const Value *Operand, const Instruction *I,
diff --git a/llvm/test/Other/print-inst-addrs.ll b/llvm/test/Other/print-inst-addrs.ll
new file mode 100644
index 0000000000000..5907b30f0f12c
--- /dev/null
+++ b/llvm/test/Other/print-inst-addrs.ll
@@ -0,0 +1,6 @@
+; RUN: opt -S -print-inst-addrs %s | FileCheck %s
+
+define void @foo() {
+  ; CHECK: ret void ; 0x
+  ret void
+}
diff --git a/llvm/test/Other/print-inst-debug-locs.ll b/llvm/test/Other/print-inst-debug-locs.ll
new file mode 100644
index 0000000000000..93210527e27a7
--- /dev/null
+++ b/llvm/test/Other/print-inst-debug-locs.ll
@@ -0,0 +1,20 @@
+; RUN: opt -S -print-inst-debug-locs < %s | FileCheck %s
+
+define weak i32 @foo(i32 %a, i32 %b) !dbg !3 {
+entry:
+  ; CHECK: call {{.*}} ; foo.c:52
+  %sum = call i32 @fastadd(i32 %a, i32 %b), !dbg !DILocation(line: 52, scope: !3)
+  ; CHECK: ret {{.*}} ; foo.c:53
+  ret i32 %sum, !dbg !DILocation(line: 53, scope: !3)
+}
+
+declare i32 @fastadd(i32, i32)
+
+!llvm.module.flags = !{!0}
+!0 = !{i32 2, !"Debug Info Version", i32 3}
+
+!llvm.dbg.cu = !{!1}
+!1 = distinct !DICompileUnit(language: DW_LANG_C99, file: !2, emissionKind: FullDebug)
+!2 = !DIFile(filename: "foo.c", directory: "/path/to/dir")
+!3 = distinct !DISubprogram(file: !2, scope: !2, line: 51, name: "foo", type: !4, unit: !1)
+!4 = !DISubroutineType(types: !{})
diff --git a/llvm/test/Other/print-mi-addrs.ll b/llvm/test/Other/print-mi-addrs.ll
new file mode 100644
index 0000000000000..5be006d9df282
--- /dev/null
+++ b/llvm/test/Other/print-mi-addrs.ll
@@ -0,0 +1,11 @@
+; RUN: llc -print-after=slotindexes -print-mi-addrs < %s 2>&1 | FileCheck %s
+; REQUIRES: default_triple
+
+; CHECK: IR Dump {{.*}}
+; CHECK: # Machine code for function foo{{.*}}
+
+define void @foo() {
+  ; CHECK: ; 0x
+  ret void
+}
+

[pcc]

Ping

[rnk]

Looks good. I came to say "sorry I don't have time", but I think this is pretty straightforward.