[clang] [Clang][Hexagon] Driver changes for H2+Picolibc (PR #195795)
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Fri May 8 08:48:01 PDT 2026
https://github.com/quic-k updated https://github.com/llvm/llvm-project/pull/195795
>From b76ebc837a6baa9c44eb37a831ad02b880f65f09 Mon Sep 17 00:00:00 2001
From: Kushal Pal <kushpal at qti.qualcomm.com>
Date: Tue, 5 May 2026 11:22:17 +0530
Subject: [PATCH] [Clang][Hexagon] Driver changes for H2+Picolibc
Signed-off-by: Kushal Pal <kushpal at qti.qualcomm.com>
---
clang/lib/Driver/ToolChains/Hexagon.cpp | 18 ++-
.../picolibc/hexagon-unknown-h2-elf/.keep | 0
.../hexagon-unknown-h2-elf/include/.keep | 0
.../hexagon-unknown-h2-elf/include/c++/.keep | 0
.../include/c++/v1/.keep | 0
.../test/Driver/hexagon-toolchain-picolibc.c | 118 ++++++++++++++++++
6 files changed, 133 insertions(+), 3 deletions(-)
create mode 100644 clang/test/Driver/Inputs/hexagon_tree/Tools/target/picolibc/hexagon-unknown-h2-elf/.keep
create mode 100644 clang/test/Driver/Inputs/hexagon_tree/Tools/target/picolibc/hexagon-unknown-h2-elf/include/.keep
create mode 100644 clang/test/Driver/Inputs/hexagon_tree/Tools/target/picolibc/hexagon-unknown-h2-elf/include/c++/.keep
create mode 100644 clang/test/Driver/Inputs/hexagon_tree/Tools/target/picolibc/hexagon-unknown-h2-elf/include/c++/v1/.keep
diff --git a/clang/lib/Driver/ToolChains/Hexagon.cpp b/clang/lib/Driver/ToolChains/Hexagon.cpp
index e0e5ab5c1fde7..41f03e01b69c1 100644
--- a/clang/lib/Driver/ToolChains/Hexagon.cpp
+++ b/clang/lib/Driver/ToolChains/Hexagon.cpp
@@ -414,8 +414,14 @@ constructHexagonLinkArgs(Compilation &C, const JobAction &JA,
if (!IsShared) {
if (HTC.GetCStdlibType(Args) == ToolChain::CST_Picolibc) {
SmallString<128> Crt0 = LibraryDir;
- llvm::sys::path::append(Crt0, "crt0-semihost.o");
- CmdArgs.push_back(Args.MakeArgString(Crt0));
+ if (HTC.getTriple().isOSH2()) {
+ llvm::sys::path::append(Crt0, "crt0-noflash-hosted.o");
+ CmdArgs.push_back(Args.MakeArgString(Crt0));
+ } else if (HTC.getTriple().isOSUnknown()) {
+ llvm::sys::path::append(Crt0, "crt0-semihost.o");
+ CmdArgs.push_back(Args.MakeArgString(Crt0));
+ }
+ // Known OS other than H2: no semihost crt0; OS provides its own.
} else {
if (HasStandalone) {
SmallString<128> Crt0SA = LibraryDir;
@@ -468,7 +474,13 @@ constructHexagonLinkArgs(Compilation &C, const JobAction &JA,
if (!IsShared) {
if (HTC.GetCStdlibType(Args) == ToolChain::CST_Picolibc) {
- CmdArgs.push_back("-lsemihost");
+ if (HTC.getTriple().isOSH2()) {
+ CmdArgs.push_back("-lh2");
+ CmdArgs.push_back("-lsyscall_wrapper");
+ } else if (HTC.getTriple().isOSUnknown()) {
+ CmdArgs.push_back("-lsemihost");
+ }
+ // Known OS other than H2: no semihost lib; OS provides its own.
} else {
for (StringRef Lib : OsLibs)
CmdArgs.push_back(Args.MakeArgString("-l" + Lib));
diff --git a/clang/test/Driver/Inputs/hexagon_tree/Tools/target/picolibc/hexagon-unknown-h2-elf/.keep b/clang/test/Driver/Inputs/hexagon_tree/Tools/target/picolibc/hexagon-unknown-h2-elf/.keep
new file mode 100644
index 0000000000000..e69de29bb2d1d
diff --git a/clang/test/Driver/Inputs/hexagon_tree/Tools/target/picolibc/hexagon-unknown-h2-elf/include/.keep b/clang/test/Driver/Inputs/hexagon_tree/Tools/target/picolibc/hexagon-unknown-h2-elf/include/.keep
new file mode 100644
index 0000000000000..e69de29bb2d1d
diff --git a/clang/test/Driver/Inputs/hexagon_tree/Tools/target/picolibc/hexagon-unknown-h2-elf/include/c++/.keep b/clang/test/Driver/Inputs/hexagon_tree/Tools/target/picolibc/hexagon-unknown-h2-elf/include/c++/.keep
new file mode 100644
index 0000000000000..e69de29bb2d1d
diff --git a/clang/test/Driver/Inputs/hexagon_tree/Tools/target/picolibc/hexagon-unknown-h2-elf/include/c++/v1/.keep b/clang/test/Driver/Inputs/hexagon_tree/Tools/target/picolibc/hexagon-unknown-h2-elf/include/c++/v1/.keep
new file mode 100644
index 0000000000000..e69de29bb2d1d
diff --git a/clang/test/Driver/hexagon-toolchain-picolibc.c b/clang/test/Driver/hexagon-toolchain-picolibc.c
index b8ac8a9c5c88d..8282a4da81636 100644
--- a/clang/test/Driver/hexagon-toolchain-picolibc.c
+++ b/clang/test/Driver/hexagon-toolchain-picolibc.c
@@ -118,3 +118,121 @@
// CHECK-LIBPATHS-PIC: "-L{{.*}}{{/|\\\\}}Inputs{{/|\\\\}}hexagon_tree{{/|\\\\}}Tools{{/|\\\\}}bin{{/|\\\\}}..{{/|\\\\}}target{{/|\\\\}}picolibc{{/|\\\\}}hexagon-unknown-none-elf{{/|\\\\}}lib{{/|\\\\}}v68{{/|\\\\}}G0{{/|\\\\}}pic"
// CHECK-LIBPATHS-PIC: "-L{{.*}}{{/|\\\\}}Inputs{{/|\\\\}}hexagon_tree{{/|\\\\}}Tools{{/|\\\\}}bin{{/|\\\\}}..{{/|\\\\}}target{{/|\\\\}}picolibc{{/|\\\\}}hexagon-unknown-none-elf{{/|\\\\}}lib{{/|\\\\}}v68{{/|\\\\}}G0"
// CHECK-LIBPATHS-PIC: "-L{{.*}}{{/|\\\\}}Inputs{{/|\\\\}}hexagon_tree{{/|\\\\}}Tools{{/|\\\\}}bin{{/|\\\\}}..{{/|\\\\}}target{{/|\\\\}}picolibc{{/|\\\\}}hexagon-unknown-none-elf{{/|\\\\}}lib{{/|\\\\}}v68"
+
+// =============================================================================
+// H2 OS tests (--target=hexagon-h2-elf --cstdlib=picolibc)
+// Differences from hexagon-none-elf: crt0-noflash-hosted.o, -lh2 -lsyscall_wrapper
+// =============================================================================
+
+// -----------------------------------------------------------------------------
+// Test standard include paths for H2
+// -----------------------------------------------------------------------------
+// RUN: %clang -### --target=hexagon-h2-elf --cstdlib=picolibc \
+// RUN: -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin %s 2>&1 | FileCheck -check-prefix=CHECK-H2-C-INCLUDES %s
+// CHECK-H2-C-INCLUDES: "-cc1" {{.*}} "-internal-isystem" "{{.*}}{{/|\\\\}}lib{{/|\\\\}}clang{{/|\\\\}}{{[0-9]+}}{{/|\\\\}}include"
+// CHECK-H2-C-INCLUDES: "-internal-externc-isystem" "{{.*}}{{/|\\\\}}Inputs{{/|\\\\}}hexagon_tree{{/|\\\\}}Tools{{/|\\\\}}bin{{/|\\\\}}..{{/|\\\\}}target{{/|\\\\}}picolibc{{/|\\\\}}hexagon-unknown-h2-elf{{/|\\\\}}include"
+
+// RUN: %clangxx -### --target=hexagon-h2-elf --cstdlib=picolibc \
+// RUN: -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin %s 2>&1 | FileCheck -check-prefix=CHECK-H2-CXX-INCLUDES %s
+// CHECK-H2-CXX-INCLUDES: "-cc1" {{.*}} "-internal-isystem" "{{.*}}{{/|\\\\}}Inputs{{/|\\\\}}hexagon_tree{{/|\\\\}}Tools{{/|\\\\}}bin{{/|\\\\}}..{{/|\\\\}}target{{/|\\\\}}picolibc{{/|\\\\}}hexagon-unknown-h2-elf{{/|\\\\}}include{{/|\\\\}}c++{{/|\\\\}}v1"
+// CHECK-H2-CXX-INCLUDES: "-internal-isystem" "{{.*}}{{/|\\\\}}lib{{/|\\\\}}clang{{/|\\\\}}{{[0-9]+}}{{/|\\\\}}include"
+// CHECK-H2-CXX-INCLUDES: "-internal-externc-isystem" "{{.*}}{{/|\\\\}}Inputs{{/|\\\\}}hexagon_tree{{/|\\\\}}Tools{{/|\\\\}}bin{{/|\\\\}}..{{/|\\\\}}target{{/|\\\\}}picolibc{{/|\\\\}}hexagon-unknown-h2-elf{{/|\\\\}}include"
+
+// -----------------------------------------------------------------------------
+// H2 start files: crt0-noflash-hosted.o (not crt0-semihost.o)
+// -----------------------------------------------------------------------------
+// RUN: %clang --target=hexagon-h2-elf --cstdlib=picolibc -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-H2-STARTUP
+// CHECK-H2-STARTUP: "{{.*}}crt0-noflash-hosted.o"
+// CHECK-H2-STARTUP-NOT: "{{.*}}crt0-semihost.o"
+
+// RUN: %clang --target=hexagon-h2-elf --cstdlib=picolibc -nostartfiles -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-H2-NOSTART
+// CHECK-H2-NOSTART-NOT: "{{.*}}crt0-noflash-hosted.o"
+
+// -----------------------------------------------------------------------------
+// H2: -nostdlib, -nostartfiles, -nodefaultlibs, -nolibc
+// -----------------------------------------------------------------------------
+// RUN: %clangxx -### --target=hexagon-h2-elf --cstdlib=picolibc \
+// RUN: -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin \
+// RUN: -mcpu=hexagonv68 \
+// RUN: -nostdlib %s 2>&1 | FileCheck -check-prefix=CHECK-H2-NOSTDLIB %s
+// CHECK-H2-NOSTDLIB: "-cc1"
+// CHECK-H2-NOSTDLIB: {{hexagon-link|ld}}
+// CHECK-H2-NOSTDLIB-NOT: "{{.*}}crt0-noflash-hosted.o"
+// CHECK-H2-NOSTDLIB-NOT: "-lc++"
+// CHECK-H2-NOSTDLIB-NOT: "-lm"
+// CHECK-H2-NOSTDLIB-NOT: "--start-group"
+// CHECK-H2-NOSTDLIB-NOT: "-lh2"
+// CHECK-H2-NOSTDLIB-NOT: "-lsyscall_wrapper"
+// CHECK-H2-NOSTDLIB-NOT: "-lc"
+// CHECK-H2-NOSTDLIB-NOT: "-lclang_rt.builtins"
+// CHECK-H2-NOSTDLIB-NOT: "--end-group"
+
+// RUN: %clangxx -### --target=hexagon-h2-elf --cstdlib=picolibc \
+// RUN: -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin \
+// RUN: -mcpu=hexagonv68 \
+// RUN: -nostartfiles %s 2>&1 | FileCheck -check-prefix=CHECK-H2-NOSTARTFILES %s
+// CHECK-H2-NOSTARTFILES: "-cc1"
+// CHECK-H2-NOSTARTFILES: {{hexagon-link|ld}}
+// CHECK-H2-NOSTARTFILES-NOT: "{{.*}}crt0-noflash-hosted.o"
+// CHECK-H2-NOSTARTFILES: "-lc++" "-lc++abi" "-lunwind" "-lm" "--start-group" "-lh2" "-lsyscall_wrapper" "-lc" "-lclang_rt.builtins" "--end-group"
+
+// RUN: %clangxx -### --target=hexagon-h2-elf --cstdlib=picolibc \
+// RUN: -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin \
+// RUN: -mcpu=hexagonv68 \
+// RUN: -nodefaultlibs %s 2>&1 | FileCheck -check-prefix=CHECK-H2-NODEFAULTLIBS %s
+// CHECK-H2-NODEFAULTLIBS: "-cc1"
+// CHECK-H2-NODEFAULTLIBS: {{hexagon-link|ld}}
+// CHECK-H2-NODEFAULTLIBS: "{{.*}}crt0-noflash-hosted.o"
+// CHECK-H2-NODEFAULTLIBS-NOT: "-lc++"
+// CHECK-H2-NODEFAULTLIBS-NOT: "-lm"
+// CHECK-H2-NODEFAULTLIBS-NOT: "--start-group"
+// CHECK-H2-NODEFAULTLIBS-NOT: "-lh2"
+// CHECK-H2-NODEFAULTLIBS-NOT: "-lsyscall_wrapper"
+// CHECK-H2-NODEFAULTLIBS-NOT: "-lc"
+// CHECK-H2-NODEFAULTLIBS-NOT: "-lclang_rt.builtins"
+// CHECK-H2-NODEFAULTLIBS-NOT: "--end-group"
+
+// RUN: %clangxx -### --target=hexagon-h2-elf --cstdlib=picolibc \
+// RUN: -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin \
+// RUN: -mcpu=hexagonv68 \
+// RUN: -nolibc %s 2>&1 | FileCheck -check-prefix=CHECK-H2-NOLIBC %s
+// CHECK-H2-NOLIBC: "-cc1"
+// CHECK-H2-NOLIBC: {{hexagon-link|ld}}
+// CHECK-H2-NOLIBC: "{{.*}}crt0-noflash-hosted.o"
+// CHECK-H2-NOLIBC-SAME: "-lc++"
+// CHECK-H2-NOLIBC-SAME: "-lm"
+// CHECK-H2-NOLIBC-SAME: "--start-group"
+// CHECK-H2-NOLIBC-SAME: "-lh2"
+// CHECK-H2-NOLIBC-SAME: "-lsyscall_wrapper"
+// CHECK-H2-NOLIBC-NOT: "-lc"
+// CHECK-H2-NOLIBC-SAME: "-lclang_rt.builtins"
+// CHECK-H2-NOLIBC-SAME: "--end-group"
+
+// -----------------------------------------------------------------------------
+// H2: compiler-rt is forced (not -lgcc)
+// -----------------------------------------------------------------------------
+// RUN: %clang --target=hexagon-h2-elf --cstdlib=picolibc -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-H2-RTLIB
+// RUN: %clangxx --target=hexagon-h2-elf --cstdlib=picolibc -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-H2-RTLIB
+// CHECK-H2-RTLIB: "-lclang_rt.builtins"
+// CHECK-H2-RTLIB-NOT: "-lgcc"
+
+// -----------------------------------------------------------------------------
+// H2: libunwind linked for C++ but not C
+// -----------------------------------------------------------------------------
+// RUN: %clangxx --target=hexagon-h2-elf --cstdlib=picolibc -### %s 2>&1 | FileCheck %s --check-prefix=CHECK-H2-CXX-UNWIND
+// CHECK-H2-CXX-UNWIND: "-lunwind"
+
+// -----------------------------------------------------------------------------
+// H2: library search paths use target/picolibc/hexagon-unknown-h2-elf/
+// -----------------------------------------------------------------------------
+// RUN: %clang --target=hexagon-h2-elf --cstdlib=picolibc \
+// RUN: -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin \
+// RUN: -mcpu=hexagonv68 -### %s 2>&1 | FileCheck -check-prefix=CHECK-H2-LIBPATHS %s
+// CHECK-H2-LIBPATHS: "-L{{.*}}{{/|\\\\}}Inputs{{/|\\\\}}hexagon_tree{{/|\\\\}}Tools{{/|\\\\}}bin{{/|\\\\}}..{{/|\\\\}}target{{/|\\\\}}picolibc{{/|\\\\}}hexagon-unknown-h2-elf{{/|\\\\}}lib{{/|\\\\}}v68"
+// CHECK-H2-LIBPATHS-NOT: "-L{{.*}}{{/|\\\\}}Inputs{{/|\\\\}}hexagon_tree{{/|\\\\}}Tools{{/|\\\\}}bin{{/|\\\\}}..{{/|\\\\}}target{{/|\\\\}}picolibc{{/|\\\\}}hexagon-unknown-h2-elf{{/|\\\\}}lib{{/|\\\\}}v68{{/|\\\\}}G0"
+
+// RUN: %clang --target=hexagon-h2-elf --cstdlib=picolibc \
+// RUN: -ccc-install-dir %S/Inputs/hexagon_tree/Tools/bin \
+// RUN: -mcpu=hexagonv68 -G0 -### %s 2>&1 | FileCheck -check-prefix=CHECK-H2-LIBPATHS-G0 %s
+// CHECK-H2-LIBPATHS-G0: "-L{{.*}}{{/|\\\\}}Inputs{{/|\\\\}}hexagon_tree{{/|\\\\}}Tools{{/|\\\\}}bin{{/|\\\\}}..{{/|\\\\}}target{{/|\\\\}}picolibc{{/|\\\\}}hexagon-unknown-h2-elf{{/|\\\\}}lib{{/|\\\\}}v68{{/|\\\\}}G0"
+// CHECK-H2-LIBPATHS-G0: "-L{{.*}}{{/|\\\\}}Inputs{{/|\\\\}}hexagon_tree{{/|\\\\}}Tools{{/|\\\\}}bin{{/|\\\\}}..{{/|\\\\}}target{{/|\\\\}}picolibc{{/|\\\\}}hexagon-unknown-h2-elf{{/|\\\\}}lib{{/|\\\\}}v68"
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