[clang] [PS4, PS5][Driver] Pass `-L<...>/target/lib -L.` to linker (PR #109796)

[Edd Dawson via cfe-commits]

https://github.com/playstation-edd created https://github.com/llvm/llvm-project/pull/109796

The proprietary PS4 linker implicitly adds `=/target/lib` and `.` as library search paths. This behaviour was added to the PS5 linker via a downstream patch in LLD. This really belongs in the driver, instead. This change adds the driver behaviour to allow removal of the downstream patch in LLD.

There are no plans to update the PS4 linker behaviour in the analogous way, so do not pass the same search paths to the PS4 linker.

SIE tracker: TOOLCHAIN-16704

>From 89ff568fda0062a89ed690cdb0267fc41a89325c Mon Sep 17 00:00:00 2001
From: Edd Dawson <edd.dawson at sony.com>
Date: Tue, 24 Sep 2024 13:05:39 +0100
Subject: [PATCH] [PS4,PS5][Driver] Pass `-L<...>/target/lib -L.` to linker

The proprietary PS4 linker implicitly adds `=/target/lib` and `.` as
library search paths. This behaviour was added to the PS5 linker via a
downstream patch in LLD. This really belongs in the driver, instead.
This change adds the driver behaviour to allow removal of the downstream
patch in LLD.

There are no plans to update the PS4 linker behaviour in the analogous
way, so do not pass the same search paths to the PS4 linker.

SIE tracker: TOOLCHAIN-16704
---
 clang/lib/Driver/ToolChains/PS4CPU.cpp |  6 ++++++
 clang/test/Driver/ps5-linker.c         | 23 +++++++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/clang/lib/Driver/ToolChains/PS4CPU.cpp b/clang/lib/Driver/ToolChains/PS4CPU.cpp
index 647580e4e235dc..0a43ab19b434c5 100644
--- a/clang/lib/Driver/ToolChains/PS4CPU.cpp
+++ b/clang/lib/Driver/ToolChains/PS4CPU.cpp
@@ -186,6 +186,9 @@ void tools::PS4cpu::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs))
     TC.addSanitizerArgs(Args, CmdArgs, "-l", "");
 
+  // Other drivers typically add library search paths (`-L`) here via
+  // TC.AddFilePathLibArgs(). We don't do that on PS4 as the PS4 linker
+  // searches those locations by default.
   Args.addAllArgs(CmdArgs, {options::OPT_L, options::OPT_T_Group,
                             options::OPT_s, options::OPT_t});
 
@@ -290,6 +293,7 @@ void tools::PS5cpu::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs))
     TC.addSanitizerArgs(Args, CmdArgs, "-l", "");
 
+  TC.AddFilePathLibArgs(Args, CmdArgs);
   Args.addAllArgs(CmdArgs, {options::OPT_L, options::OPT_T_Group,
                             options::OPT_s, options::OPT_t});
 
@@ -382,6 +386,8 @@ toolchains::PS4PS5Base::PS4PS5Base(const Driver &D, const llvm::Triple &Triple,
     llvm::sys::path::append(Dir, "target/include");
     CheckSDKPartExists(Dir, "system headers");
   }
+
+  getFilePaths().push_back(".");
 }
 
 void toolchains::PS4PS5Base::AddClangSystemIncludeArgs(
diff --git a/clang/test/Driver/ps5-linker.c b/clang/test/Driver/ps5-linker.c
index c0cf0b864028c8..852659ae86d5cf 100644
--- a/clang/test/Driver/ps5-linker.c
+++ b/clang/test/Driver/ps5-linker.c
@@ -46,3 +46,26 @@
 
 // CHECK-SYSROOT: {{ld(\.exe)?}}"
 // CHECK-SYSROOT-SAME: "--sysroot=mysdk"
+
+// Test that "." is always added to library search paths. This is long-standing
+// behavior, unique to PlayStation toolchains.
+
+// RUN: %clang --target=x64_64-sie-ps5 %s -### 2>&1 | FileCheck --check-prefixes=CHECK-LDOT %s
+
+// CHECK-LDOT: {{ld(\.exe)?}}"
+// CHECK-LDOT-SAME: "-L."
+
+// Test that <sdk-root>/target/lib is added to library search paths, if it
+// exists and no --sysroot is specified.
+
+// RUN: rm -rf %t.dir && mkdir -p %t.dir/target/lib
+// RUN: env SCE_PROSPERO_SDK_DIR=%t.dir %clang --target=x64_64-sie-ps5 %s -### 2>&1 | FileCheck --check-prefixes=CHECK-TARGETLIB %s
+
+// CHECK-TARGETLIB: {{ld(\.exe)?}}"
+// CHECK-TARGETLIB-SAME: "-L{{.*[/\\]}}target/lib"
+
+// RUN: env SCE_PROSPERO_SDK_DIR=missing %clang --target=x64_64-sie-ps5 %s -### 2>&1 | FileCheck --check-prefixes=CHECK-NO-TARGETLIB %s
+// RUN: env SCE_PROSPERO_SDK_DIR=%t.dir %clang --target=x64_64-sie-ps5 %s -### --sysroot=missing 2>&1 | FileCheck --check-prefixes=CHECK-NO-TARGETLIB %s
+
+// CHECK-NO-TARGETLIB: {{ld(\.exe)?}}"
+// CHECK-NO-TARGETLIB-NOT: "-L{{.*[/\\]}}target/lib"