[llvm] Optionally print `!prof` metadata inline (PR #130303)

[Mircea Trofin via llvm-commits]

https://github.com/mtrofin created https://github.com/llvm/llvm-project/pull/130303

None

>From e5ac263218208c7521d44e2a0a8ab617f4c7d8ef Mon Sep 17 00:00:00 2001
From: Mircea Trofin <mtrofin at google.com>
Date: Fri, 7 Mar 2025 08:19:31 -0800
Subject: [PATCH] Optionally print `!prof` metadata inline

---
 llvm/lib/IR/AsmWriter.cpp          | 17 +++++++++++++++++
 llvm/test/Other/print-prof-data.ll | 24 ++++++++++++++++++++++++
 llvm/test/Other/print-prof-data.s  | 23 +++++++++++++++++++++++
 3 files changed, 64 insertions(+)
 create mode 100644 llvm/test/Other/print-prof-data.ll
 create mode 100644 llvm/test/Other/print-prof-data.s

diff --git a/llvm/lib/IR/AsmWriter.cpp b/llvm/lib/IR/AsmWriter.cpp
index 88bb2359cd055..8399fa8a98f80 100644
--- a/llvm/lib/IR/AsmWriter.cpp
+++ b/llvm/lib/IR/AsmWriter.cpp
@@ -96,6 +96,10 @@ static cl::opt<bool> PrintInstDebugLocs(
     "print-inst-debug-locs", cl::Hidden,
     cl::desc("Pretty print debug locations of instructions when dumping"));
 
+static cl::opt<bool> PrintPerfData(
+    "print-perf-data", cl::Hidden,
+    cl::desc("Pretty print perf data (branch weights, etc) when dumping"));
+
 // Make virtual table appear in this compilation unit.
 AssemblyAnnotationWriter::~AssemblyAnnotationWriter() = default;
 
@@ -4161,6 +4165,11 @@ void AssemblyWriter::printFunction(const Function *F) {
     writeOperand(F->getPersonalityFn(), /*PrintType=*/true);
   }
 
+  if (PrintPerfData && F->getEntryCount()) {
+    Out << " ";
+    F->getMetadata(LLVMContext::MD_prof)->print(Out, TheModule, true);
+  }
+
   if (F->isDeclaration()) {
     Out << '\n';
   } else {
@@ -4287,6 +4296,14 @@ void AssemblyWriter::printInfoComment(const Value &V) {
       }
     }
   }
+  if (PrintPerfData) {
+    if (auto *I = dyn_cast<Instruction>(&V)) {
+      if (auto *MD = I->getMetadata(LLVMContext::MD_prof)) {
+        Out << " ; ";
+        MD->print(Out, TheModule, true);
+      }
+    }
+  }
 
   if (PrintInstAddrs)
     Out << " ; " << &V;
diff --git a/llvm/test/Other/print-prof-data.ll b/llvm/test/Other/print-prof-data.ll
new file mode 100644
index 0000000000000..a5a2d444222b5
--- /dev/null
+++ b/llvm/test/Other/print-prof-data.ll
@@ -0,0 +1,24 @@
+; RUN: opt %s -print-prof-data -S | FileCheck %s
+
+define void @foo(ptr %p) !prof !0 {
+  %isnull = icmp eq ptr %p, null
+  br i1 %isnull, label %yes, label %no, !prof !1
+yes:
+  %something = select i1 %isnull, i32 1, i32 2, !prof !2
+  br label %exit
+no:
+  call void %p(), !prof !3
+  br label %exit
+exit:
+  ret void
+}
+
+!0 = !{!"function_entry_count", i64 42}
+!1 = !{!"branch_weights", i64 20, i64 101}
+!2 = !{!"branch_weights", i64 5, i64 70}
+!3 = !{!"VP", i32 0, i64 4, i64 4445083295448962937, i64 2, i64 -2718743882639408571, i64 2}
+
+; CHECK: define void @foo(ptr %p) !0 = !{!"function_entry_count", i64 42} !prof !0 {
+; CHECK: br i1 %isnull, label %yes, label %no, !prof !1 ; !1 = !{!"branch_weights", i64 20, i64 101}
+; CHECK: %something = select i1 %isnull, i32 1, i32 2, !prof !2 ; !2 = !{!"branch_weights", i64 5, i64 70}
+; CHECK: call void %p(), !prof !3 ; !3 = !{!"VP", i32 0, i64 4, i64 4445083295448962937, i64 2, i64 -2718743882639408571, i64 2}
\ No newline at end of file
diff --git a/llvm/test/Other/print-prof-data.s b/llvm/test/Other/print-prof-data.s
new file mode 100644
index 0000000000000..79595393eab2c
--- /dev/null
+++ b/llvm/test/Other/print-prof-data.s
@@ -0,0 +1,23 @@
+	.file	"print-prof-data.ll"
+	.text
+	.globl	foo                             # -- Begin function foo
+	.p2align	4
+	.type	foo, at function
+foo:                                    # @foo
+	.cfi_startproc
+# %bb.0:
+	testq	%rdi, %rdi
+	je	.LBB0_2
+# %bb.1:                                # %no
+	pushq	%rax
+	.cfi_def_cfa_offset 16
+	callq	*%rdi
+	addq	$8, %rsp
+	.cfi_def_cfa_offset 8
+.LBB0_2:                                # %exit
+	retq
+.Lfunc_end0:
+	.size	foo, .Lfunc_end0-foo
+	.cfi_endproc
+                                        # -- End function
+	.section	".note.GNU-stack","", at progbits