[clang] 3ce06b8 - [Clang][Driver] Expose relocation model as multilib flags (#149132)
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cfe-commits at lists.llvm.org
Fri Jul 18 01:34:46 PDT 2025
Author: Simon Tatham
Date: 2025-07-18T09:34:42+01:00
New Revision: 3ce06b8c2196be6368f0e06862ac1849379cce41
URL: https://github.com/llvm/llvm-project/commit/3ce06b8c2196be6368f0e06862ac1849379cce41
DIFF: https://github.com/llvm/llvm-project/commit/3ce06b8c2196be6368f0e06862ac1849379cce41.diff
LOG: [Clang][Driver] Expose relocation model as multilib flags (#149132)
If a multilib collection contains libraries built for different methods
of accessing global data (via absolute address, or via a GOT in -fPIC
style, or as an offset from a fixed register in Arm -frwpi style), then
`multilib.yaml` will need to know which relocation model an application
is using in order to select the right library.
Even if a multilib collection only supports one relocation model, it's
still useful for `multilib.yaml` to be able to tell if the user has
selected the right one, so as to give a useful error message if they
haven't, instead of silently selecting a library that won't work.
In this commit we determine the PIC / ROPI / RWPI status using the
existing logic in `ParsePICArgs`, and translate it back into a canonical
set of multilib selection flags.
Added:
Modified:
clang/lib/Driver/ToolChain.cpp
clang/test/Driver/print-multi-selection-flags.c
Removed:
################################################################################
diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index 3f9b808b2722e..481f575518b93 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -258,10 +258,10 @@ static void getAArch64MultilibFlags(const Driver &D,
processMultilibCustomFlags(Result, Args);
}
-static void getARMMultilibFlags(const Driver &D,
- const llvm::Triple &Triple,
- const llvm::opt::ArgList &Args,
- Multilib::flags_list &Result) {
+static void getARMMultilibFlags(const Driver &D, const llvm::Triple &Triple,
+ llvm::Reloc::Model RelocationModel,
+ const llvm::opt::ArgList &Args,
+ Multilib::flags_list &Result) {
std::vector<StringRef> Features;
llvm::ARM::FPUKind FPUKind = tools::arm::getARMTargetFeatures(
D, Triple, Args, Features, false /*ForAs*/, true /*ForMultilib*/);
@@ -304,6 +304,18 @@ static void getARMMultilibFlags(const Driver &D,
llvm_unreachable("Invalid float ABI");
}
+ if (RelocationModel == llvm::Reloc::ROPI ||
+ RelocationModel == llvm::Reloc::ROPI_RWPI)
+ Result.push_back("-fropi");
+ else
+ Result.push_back("-fno-ropi");
+
+ if (RelocationModel == llvm::Reloc::RWPI ||
+ RelocationModel == llvm::Reloc::ROPI_RWPI)
+ Result.push_back("-frwpi");
+ else
+ Result.push_back("-fno-rwpi");
+
const Arg *BranchProtectionArg =
Args.getLastArgNoClaim(options::OPT_mbranch_protection_EQ);
if (BranchProtectionArg) {
@@ -344,6 +356,18 @@ ToolChain::getMultilibFlags(const llvm::opt::ArgList &Args) const {
const llvm::Triple Triple(ComputeEffectiveClangTriple(Args));
Result.push_back("--target=" + Triple.str());
+ // A
diff erence of relocation model (absolutely addressed data, PIC, Arm
+ // ROPI/RWPI) is likely to change whether a particular multilib variant is
+ // compatible with a given link. Determine the relocation model of the
+ // current link, so as to add appropriate multilib flags.
+ llvm::Reloc::Model RelocationModel;
+ unsigned PICLevel;
+ bool IsPIE;
+ {
+ RegisterEffectiveTriple TripleRAII(*this, Triple);
+ std::tie(RelocationModel, PICLevel, IsPIE) = ParsePICArgs(*this, Args);
+ }
+
switch (Triple.getArch()) {
case llvm::Triple::aarch64:
case llvm::Triple::aarch64_32:
@@ -354,7 +378,7 @@ ToolChain::getMultilibFlags(const llvm::opt::ArgList &Args) const {
case llvm::Triple::armeb:
case llvm::Triple::thumb:
case llvm::Triple::thumbeb:
- getARMMultilibFlags(D, Triple, Args, Result);
+ getARMMultilibFlags(D, Triple, RelocationModel, Args, Result);
break;
case llvm::Triple::riscv32:
case llvm::Triple::riscv64:
@@ -376,6 +400,12 @@ ToolChain::getMultilibFlags(const llvm::opt::ArgList &Args) const {
else
Result.push_back("-fexceptions");
+ if (RelocationModel == llvm::Reloc::PIC_)
+ Result.push_back(IsPIE ? (PICLevel > 1 ? "-fPIE" : "-fpie")
+ : (PICLevel > 1 ? "-fPIC" : "-fpic"));
+ else
+ Result.push_back("-fno-pic");
+
// Sort and remove duplicates.
std::sort(Result.begin(), Result.end());
Result.erase(llvm::unique(Result), Result.end());
diff --git a/clang/test/Driver/print-multi-selection-flags.c b/clang/test/Driver/print-multi-selection-flags.c
index 5f9383fbed8f4..8cf8f04bb6b48 100644
--- a/clang/test/Driver/print-multi-selection-flags.c
+++ b/clang/test/Driver/print-multi-selection-flags.c
@@ -107,3 +107,22 @@
// CHECK-AARCH64-MULTILIB-CUSTOM-FLAG: --target=aarch64-unknown-none-eabi
// CHECK-MULTILIB-CUSTOM-FLAG-DAG: -fmultilib-flag=foo
// CHECK-MULTILIB-CUSTOM-FLAG-DAG: -fmultilib-flag=bar
+
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -fropi | FileCheck --check-prefixes=CHECK-ROPI,CHECK-NO-RWPI,CHECK-NO-PIC %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -frwpi | FileCheck --check-prefixes=CHECK-NO-ROPI,CHECK-RWPI,CHECK-NO-PIC %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -fropi -frwpi | FileCheck --check-prefixes=CHECK-ROPI,CHECK-RWPI,CHECK-NO-PIC %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -fno-ropi -fno-rwpi | FileCheck --check-prefixes=CHECK-NO-ROPI,CHECK-NO-RWPI,CHECK-NO-PIC %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a | FileCheck --check-prefixes=CHECK-NO-ROPI,CHECK-NO-RWPI,CHECK-NO-PIC %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -fpic | FileCheck --check-prefixes=CHECK-NO-ROPI,CHECK-NO-RWPI,CHECK-PIC1 %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -fPIC | FileCheck --check-prefixes=CHECK-NO-ROPI,CHECK-NO-RWPI,CHECK-PIC2 %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -fpie | FileCheck --check-prefixes=CHECK-NO-ROPI,CHECK-NO-RWPI,CHECK-PIE1 %s
+// RUN: %clang -multi-lib-config=%S/Inputs/multilib/empty.yaml -print-multi-flags-experimental --target=arm-none-eabi -march=armv7a -fPIE | FileCheck --check-prefixes=CHECK-NO-ROPI,CHECK-NO-RWPI,CHECK-PIE2 %s
+// CHECK-PIC2: -fPIC
+// CHECK-PIE2: -fPIE
+// CHECK-NO-PIC: -fno-pic
+// CHECK-NO-ROPI: -fno-ropi
+// CHECK-NO-RWPI: -fno-rwpi
+// CHECK-PIC1: -fpic
+// CHECK-PIE1: -fpie
+// CHECK-ROPI: -fropi
+// CHECK-RWPI: -frwpi
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