From: Dean Michael Berris <dberris@google.com>
Date: Mon, 6 Mar 2017 06:48:56 +0000 (+0000)
Subject: [XRay] Allow logging the first argument of a function call.
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=8c95619c81a645d9305741485f21fa2a908152b5;p=llvm

[XRay] Allow logging the first argument of a function call.

Summary:
Functions with the "xray-log-args" attribute will have a special XRay sled kind
emitted, for compiler-rt to copy any call arguments to your logging handler.

For practical and performance reasons, only the first argument is supported, and
only up to 64 bits.

Reviewers: dberris

Reviewed By: dberris

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D29702

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@296998 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/include/llvm/CodeGen/AsmPrinter.h b/include/llvm/CodeGen/AsmPrinter.h
index 1fc68d061a4..babb1ca1771 100644
--- a/include/llvm/CodeGen/AsmPrinter.h
+++ b/include/llvm/CodeGen/AsmPrinter.h
@@ -222,6 +222,7 @@ public:
     FUNCTION_ENTER = 0,
     FUNCTION_EXIT = 1,
     TAIL_CALL = 2,
+    LOG_ARGS_ENTER = 3,
   };
 
   // The table will contain these structs that point to the sled, the function
diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index b8a8a999c42..7099065a638 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -2756,8 +2756,11 @@ void AsmPrinter::recordSled(MCSymbol *Sled, const MachineInstr &MI,
   SledKind Kind) {
   auto Fn = MI.getParent()->getParent()->getFunction();
   auto Attr = Fn->getFnAttribute("function-instrument");
+  bool LogArgs = Fn->hasFnAttribute("xray-log-args");
   bool AlwaysInstrument =
     Attr.isStringAttribute() && Attr.getValueAsString() == "xray-always";
+  if (Kind == SledKind::FUNCTION_ENTER && LogArgs)
+    Kind = SledKind::LOG_ARGS_ENTER;
   Sleds.emplace_back(
     XRayFunctionEntry{ Sled, CurrentFnSym, Kind, AlwaysInstrument, Fn });
 }
diff --git a/test/CodeGen/X86/xray-log-args.ll b/test/CodeGen/X86/xray-log-args.ll
new file mode 100644
index 00000000000..a551868ffb4
--- /dev/null
+++ b/test/CodeGen/X86/xray-log-args.ll
@@ -0,0 +1,35 @@
+; When logging arguments is specified, emit the entry sled accordingly.
+
+; RUN: llc -filetype=asm -o - -mtriple=x86_64-unknown-linux-gnu < %s | FileCheck %s
+; RUN: llc -filetype=asm -o - -mtriple=x86_64-darwin-unknown < %s | FileCheck %s
+
+define i32 @callee(i32 %arg) nounwind noinline uwtable "function-instrument"="xray-always" "xray-log-args"="1" {
+  ret i32 %arg
+}
+; CHECK-LABEL: Lxray_synthetic_0:
+; CHECK:	.quad	{{\.?}}Lxray_sled_0
+; CHECK:	.quad	{{_?}}callee
+; CHECK:	.byte	3
+; CHECK:	.byte	1
+; CHECK:	.{{(zero|space)}}	14
+; CHECK:	.quad	{{\.?}}Lxray_sled_1
+; CHECK:	.quad	{{_?}}callee
+; CHECK:	.byte	1
+; CHECK:	.byte	1
+; CHECK:	.{{(zero|space)}}	14
+
+define i32 @caller(i32 %arg) nounwind noinline uwtable "function-instrument"="xray-always" "xray-log-args"="1" {
+  %retval = tail call i32 @callee(i32 %arg)
+  ret i32 %retval
+}
+; CHECK-LABEL: Lxray_synthetic_1:
+; CHECK:	.quad	{{\.?}}Lxray_sled_2
+; CHECK:	.quad	{{_?}}caller
+; CHECK:	.byte	3
+; CHECK:	.byte	1
+; CHECK:	.{{(zero|space)}}	14
+; CHECK:	.quad	{{\.?}}Lxray_sled_3
+; CHECK:	.quad	{{_?}}caller
+; CHECK:	.byte	2
+; CHECK:	.byte	1
+; CHECK:	.{{(zero|space)}}	14