[Clang][Driver][LTO] Change the filename format for LTO'd stats file

[mshockwave]

Use ".ld.stats" instead of ".stats" for stats file generated by LTO backend. The new extension makes it easier to search for LTO'd stats file and be consistent with LTO'd optimization remarks files' naming convention (i.e. *.opt.ld.yaml, as opposed to *.opt.yaml for normal opt remarks files).

[llvmbot]

@llvm/pr-subscribers-clang-driver

@llvm/pr-subscribers-clang

Author: Min-Yih Hsu (mshockwave)

Changes

Use "<output filename>.ld.stats" instead of "<base input filename>.stats" for stats file generated by LTO backend. The new extension makes it easier to search for LTO'd stats file and be consistent with LTO'd optimization remarks files' naming convention (i.e. *.opt.ld.yaml, as opposed to *.opt.yaml for normal opt remarks files).

---

Full diff: https://github.com/llvm/llvm-project/pull/70242.diff

3 Files Affected:

• (modified) clang/lib/Driver/ToolChains/CommonArgs.cpp (+15-4)
• (modified) clang/lib/Driver/ToolChains/CommonArgs.h (+2-1)
• (modified) clang/test/Driver/save-stats.c (+3-2)

diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index ad012d3d0d4b46f..98e20abc015c5fd 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -852,7 +852,8 @@ void tools::addLTOOptions(const ToolChain &ToolChain, const ArgList &Args,
         Args.MakeArgString(Twine(PluginOptPrefix) + "-stack-size-section"));
 
   // Setup statistics file output.
-  SmallString<128> StatsFile = getStatsFileName(Args, Output, Input, D);
+  SmallString<128> StatsFile =
+      getStatsFileName(Args, Output, Input, D, /*IsLTO=*/true);
   if (!StatsFile.empty())
     CmdArgs.push_back(
         Args.MakeArgString(Twine(PluginOptPrefix) + "stats-file=" + StatsFile));
@@ -1941,7 +1942,7 @@ void tools::AddRunTimeLibs(const ToolChain &TC, const Driver &D,
 SmallString<128> tools::getStatsFileName(const llvm::opt::ArgList &Args,
                                          const InputInfo &Output,
                                          const InputInfo &Input,
-                                         const Driver &D) {
+                                         const Driver &D, bool IsLTO) {
   const Arg *A = Args.getLastArg(options::OPT_save_stats_EQ);
   if (!A && !D.CCPrintInternalStats)
     return {};
@@ -1957,9 +1958,19 @@ SmallString<128> tools::getStatsFileName(const llvm::opt::ArgList &Args,
       return {};
     }
 
-    StringRef BaseName = llvm::sys::path::filename(Input.getBaseInput());
+    StringRef BaseName;
+    // For stats files generated by the LTO backend, we're using "<output
+    // filename>.ld.stats" for its name. Note that we don't query
+    // `options::OPT_flto_EQ` and `options::OPT_fno_lto` here to decide `IsLTO`
+    // because it also changes the stats filenames for the pre-link object (LLVM
+    // bitcode) files, which we want to keep the same.
+    if (IsLTO && Output.isFilename())
+      BaseName = llvm::sys::path::filename(Output.getFilename());
+    else
+      BaseName = llvm::sys::path::filename(Input.getBaseInput());
+
     llvm::sys::path::append(StatsFile, BaseName);
-    llvm::sys::path::replace_extension(StatsFile, "stats");
+    llvm::sys::path::replace_extension(StatsFile, IsLTO ? "ld.stats" : "stats");
   } else {
     assert(D.CCPrintInternalStats);
     StatsFile.assign(D.CCPrintInternalStatReportFilename.empty()
diff --git a/clang/lib/Driver/ToolChains/CommonArgs.h b/clang/lib/Driver/ToolChains/CommonArgs.h
index f364c9793c9be62..bab80af5fb2f67a 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.h
+++ b/clang/lib/Driver/ToolChains/CommonArgs.h
@@ -184,7 +184,8 @@ SmallVector<StringRef> unifyTargetFeatures(ArrayRef<StringRef> Features);
 /// to.
 SmallString<128> getStatsFileName(const llvm::opt::ArgList &Args,
                                   const InputInfo &Output,
-                                  const InputInfo &Input, const Driver &D);
+                                  const InputInfo &Input, const Driver &D,
+                                  bool IsLTO = false);
 
 /// \p Flag must be a flag accepted by the driver.
 void addMultilibFlag(bool Enabled, const StringRef Flag,
diff --git a/clang/test/Driver/save-stats.c b/clang/test/Driver/save-stats.c
index ca8f2a457d4488c..44a6ddabde2a2e9 100644
--- a/clang/test/Driver/save-stats.c
+++ b/clang/test/Driver/save-stats.c
@@ -22,10 +22,11 @@
 // RUN: %clang -target x86_64-linux-unknown -save-stats -flto -o obj/dir/save-stats.exe %s -### 2>&1 | FileCheck %s -check-prefix=CHECK-LTO
 // CHECK-LTO: "-stats-file=save-stats.stats"
 // CHECK-LTO: "-o" "obj/dir{{/|\\\\}}save-stats.exe"
-// CHECK-LTO: "-plugin-opt=stats-file=save-stats.stats"
+// CHECK-LTO: "-plugin-opt=stats-file=save-stats.ld.stats"
 
 // RUN: %clang -target x86_64-linux-unknown -save-stats=obj -flto -o obj/dir/save-stats.exe %s -### 2>&1 | FileCheck %s -check-prefix=CHECK-LTO-OBJ
-// CHECK-LTO-OBJ: "-plugin-opt=stats-file=obj/dir{{/|\\\\}}save-stats.stats"
+// CHECK-LTO-OBJ: "-stats-file={{.*}}save-stats.stats"
+// CHECK-LTO-OBJ: "-plugin-opt=stats-file=obj/dir{{/|\\\\}}save-stats.ld.stats"
 
 // RUN: env CC_PRINT_INTERNAL_STAT=1 \
 // RUN: %clang -target x86_64-apple-darwin %s -### 2>&1 | FileCheck %s -check-prefix=CHECK-ENV

[MaskRay]

I can understand the rationale, but adding this special case feels stranger to me..

[mshockwave]

I can understand the rationale, but adding this special case feels stranger to me..

I'm fine with not having a special file extension for LTO'd stats file, hence closing this PR.
That said, it would be really helpful if you could help me to review a related PR #71197 .