[llvm] [ctxprof] Instrumentation: handle direct call targets to aliases (PR #142657)
Mircea Trofin via llvm-commits
llvm-commits at lists.llvm.org
Wed Jun 4 10:17:09 PDT 2025
https://github.com/mtrofin updated https://github.com/llvm/llvm-project/pull/142657
>From 8a2d049b491cb87c7e9a2dc72ce5bc2dbc5a90d7 Mon Sep 17 00:00:00 2001
From: Mircea Trofin <mtrofin at google.com>
Date: Tue, 3 Jun 2025 12:21:47 -0700
Subject: [PATCH] [ctxprof] Instrument direct calls to other things than
Functions
---
llvm/include/llvm/IR/InstrTypes.h | 3 +-
llvm/include/llvm/IR/IntrinsicInst.h | 2 +-
.../PGOProfile/ctx-instrumentation-aliases.ll | 25 ++++++++++++
.../PGOProfile/ctx-instrumentation.ll | 40 +++++++++++++++++++
4 files changed, 68 insertions(+), 2 deletions(-)
create mode 100644 llvm/test/Transforms/PGOProfile/ctx-instrumentation-aliases.ll
diff --git a/llvm/include/llvm/IR/InstrTypes.h b/llvm/include/llvm/IR/InstrTypes.h
index 11aaa938f451f..14685abef01e9 100644
--- a/llvm/include/llvm/IR/InstrTypes.h
+++ b/llvm/include/llvm/IR/InstrTypes.h
@@ -1343,7 +1343,8 @@ class CallBase : public Instruction {
Use &getCalledOperandUse() { return Op<CalledOperandOpEndIdx>(); }
/// Returns the function called, or null if this is an indirect function
- /// invocation or the function signature does not match the call signature.
+ /// invocation or the function signature does not match the call signature, or
+ /// the call target is an alias.
Function *getCalledFunction() const {
if (auto *F = dyn_cast_or_null<Function>(getCalledOperand()))
if (F->getValueType() == getFunctionType())
diff --git a/llvm/include/llvm/IR/IntrinsicInst.h b/llvm/include/llvm/IR/IntrinsicInst.h
index 74bd22e70b619..20e667524fa0d 100644
--- a/llvm/include/llvm/IR/IntrinsicInst.h
+++ b/llvm/include/llvm/IR/IntrinsicInst.h
@@ -1536,7 +1536,7 @@ class InstrProfCallsite : public InstrProfCntrInstBase {
static bool canInstrumentCallsite(const CallBase &CB) {
return !CB.isInlineAsm() &&
(CB.isIndirectCall() ||
- (CB.getCalledFunction() && !CB.getCalledFunction()->isIntrinsic()));
+ (CB.getIntrinsicID() == Intrinsic::not_intrinsic));
}
LLVM_ABI Value *getCallee() const;
LLVM_ABI void setCallee(Value *Callee);
diff --git a/llvm/test/Transforms/PGOProfile/ctx-instrumentation-aliases.ll b/llvm/test/Transforms/PGOProfile/ctx-instrumentation-aliases.ll
new file mode 100644
index 0000000000000..39e2d138fb97f
--- /dev/null
+++ b/llvm/test/Transforms/PGOProfile/ctx-instrumentation-aliases.ll
@@ -0,0 +1,25 @@
+; REQUIRES: x86-registered-target
+; Test that calls to aliases are instrumented, and the assembly references the
+; aliased function.
+;
+; RUN: opt -passes=ctx-instr-gen,assign-guid,ctx-instr-lower -profile-context-root=an_entrypoint \
+; RUN: -profile-context-root=another_entrypoint_no_callees \
+; RUN: -S %s -o %t.ll
+; RUN: llc < %t.ll | FileCheck %s
+target triple = "x86_64-unknown-linux-gnu"
+
+ at foo_alias = weak_odr unnamed_addr alias void (), ptr @foo
+
+define void @foo(i32) {
+ ret void
+}
+
+define void @call_alias(ptr %a) {
+entry:
+ call void @foo(i32 0, ptr %a)
+ ret void
+}
+
+; CHECK-LABEL: call_alias:
+; CHECK: movq foo at GOTPCREL(%rip), [[REG:%r[a-z0-9]+]]
+; CHECK-NEXT: movq [[REG]], %fs:__llvm_ctx_profile_expected_callee at TPOFF{{.*}}
diff --git a/llvm/test/Transforms/PGOProfile/ctx-instrumentation.ll b/llvm/test/Transforms/PGOProfile/ctx-instrumentation.ll
index 71d54f98d26e1..a2f3d52d713dd 100644
--- a/llvm/test/Transforms/PGOProfile/ctx-instrumentation.ll
+++ b/llvm/test/Transforms/PGOProfile/ctx-instrumentation.ll
@@ -8,6 +8,8 @@
declare void @bar()
+;.
+; INSTRUMENT: @foo_alias = weak_odr unnamed_addr alias void (i32, ptr), ptr @foo
;.
; LOWERING: @__llvm_ctx_profile_callsite = external hidden thread_local global ptr
; LOWERING: @__llvm_ctx_profile_expected_callee = external hidden thread_local global ptr
@@ -19,6 +21,8 @@ declare void @bar()
; LOWERING: @[[GLOB5:[0-9]+]] = internal global { ptr, ptr, ptr, ptr, i8 } zeroinitializer
; LOWERING: @[[GLOB6:[0-9]+]] = internal global { ptr, ptr, ptr, ptr, i8 } zeroinitializer
; LOWERING: @[[GLOB7:[0-9]+]] = internal global { ptr, ptr, ptr, ptr, i8 } { ptr null, ptr null, ptr inttoptr (i64 1 to ptr), ptr null, i8 0 }
+; LOWERING: @[[GLOB8:[0-9]+]] = internal global { ptr, ptr, ptr, ptr, i8 } zeroinitializer
+; LOWERING: @foo_alias = weak_odr unnamed_addr alias void (i32, ptr), ptr @foo
;.
define void @foo(i32 %a, ptr %fct) {
; INSTRUMENT-LABEL: define void @foo(
@@ -335,6 +339,41 @@ define void @unreachable() {
;
unreachable
}
+
+ at foo_alias = weak_odr unnamed_addr alias void (i32, ptr), ptr @foo
+
+define void @call_alias(ptr %a) {
+; INSTRUMENT-LABEL: define void @call_alias(
+; INSTRUMENT-SAME: ptr [[A:%.*]]) {
+; INSTRUMENT-NEXT: entry:
+; INSTRUMENT-NEXT: call void @llvm.instrprof.increment(ptr @call_alias, i64 742261418966908927, i32 1, i32 0)
+; INSTRUMENT-NEXT: call void @llvm.instrprof.callsite(ptr @call_alias, i64 742261418966908927, i32 1, i32 0, ptr @foo_alias)
+; INSTRUMENT-NEXT: call void @foo_alias(i32 0, ptr [[A]])
+; INSTRUMENT-NEXT: ret void
+;
+; LOWERING-LABEL: define void @call_alias(
+; LOWERING-SAME: ptr [[A:%.*]]) !guid [[META10:![0-9]+]] {
+; LOWERING-NEXT: entry:
+; LOWERING-NEXT: [[TMP0:%.*]] = call ptr @__llvm_ctx_profile_get_context(ptr @[[GLOB8]], ptr @call_alias, i64 2172368043968427688, i32 1, i32 1)
+; LOWERING-NEXT: [[TMP1:%.*]] = ptrtoint ptr [[TMP0]] to i64
+; LOWERING-NEXT: [[TMP2:%.*]] = and i64 [[TMP1]], 1
+; LOWERING-NEXT: [[TMP3:%.*]] = call ptr @llvm.threadlocal.address.p0(ptr @__llvm_ctx_profile_expected_callee)
+; LOWERING-NEXT: [[TMP4:%.*]] = getelementptr ptr, ptr [[TMP3]], i64 [[TMP2]]
+; LOWERING-NEXT: [[TMP5:%.*]] = call ptr @llvm.threadlocal.address.p0(ptr @__llvm_ctx_profile_callsite)
+; LOWERING-NEXT: [[TMP6:%.*]] = getelementptr i32, ptr [[TMP5]], i64 [[TMP2]]
+; LOWERING-NEXT: [[TMP7:%.*]] = and i64 [[TMP1]], -2
+; LOWERING-NEXT: [[TMP8:%.*]] = inttoptr i64 [[TMP7]] to ptr
+; LOWERING-NEXT: store volatile ptr @foo_alias, ptr [[TMP4]], align 8
+; LOWERING-NEXT: [[TMP9:%.*]] = getelementptr { { i64, ptr, i32, i32 }, [1 x i64], [1 x ptr] }, ptr [[TMP0]], i32 0, i32 2, i32 0
+; LOWERING-NEXT: store volatile ptr [[TMP9]], ptr [[TMP6]], align 8
+; LOWERING-NEXT: call void @foo_alias(i32 0, ptr [[A]])
+; LOWERING-NEXT: call void @__llvm_ctx_profile_release_context(ptr @[[GLOB8]])
+; LOWERING-NEXT: ret void
+;
+entry:
+ call void @foo_alias(i32 0, ptr %a)
+ ret void
+}
;.
; LOWERING: attributes #[[ATTR0]] = { noreturn }
; LOWERING: attributes #[[ATTR1:[0-9]+]] = { nounwind }
@@ -353,4 +392,5 @@ define void @unreachable() {
; LOWERING: [[META7]] = !{i64 -4680624981836544329}
; LOWERING: [[META8]] = !{i64 5519225910966780583}
; LOWERING: [[META9]] = !{i64 -565652589829076809}
+; LOWERING: [[META10]] = !{i64 2172368043968427688}
;.
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