[clang][driver] Fix -fveclib=ArmPL issue: with -nostdlib do not link against libm #133578
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@llvm/pr-subscribers-clang-driver @llvm/pr-subscribers-clang Author: Paul Osmialowski (pawosm-arm) ChangesAlthough combining -fveclib=ArmPL with -nostdlib is a rare situation, it should still be supported correctly and should effect in avoidance of linking against libm. Full diff: https://github.com/llvm/llvm-project/pull/133578.diff 3 Files Affected:
diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 41cfa3d2e4f8c..5aac20e1cdf44 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -515,7 +515,7 @@ void tools::AddLinkerInputs(const ToolChain &TC, const InputInfoList &Inputs,
//
// 1. On Linux, link only when actually needed.
//
- // 2. Prefer libm functions over libamath.
+ // 2. Prefer libm functions over libamath (when no -nostdlib in use).
//
// 3. Link against libm to resolve libamath dependencies.
//
@@ -523,9 +523,11 @@ void tools::AddLinkerInputs(const ToolChain &TC, const InputInfoList &Inputs,
CmdArgs.push_back(Args.MakeArgString("--push-state"));
CmdArgs.push_back(Args.MakeArgString("--as-needed"));
}
- CmdArgs.push_back(Args.MakeArgString("-lm"));
+ if (!Args.hasArg(options::OPT_nostdlib))
+ CmdArgs.push_back(Args.MakeArgString("-lm"));
CmdArgs.push_back(Args.MakeArgString("-lamath"));
- CmdArgs.push_back(Args.MakeArgString("-lm"));
+ if (!Args.hasArg(options::OPT_nostdlib))
+ CmdArgs.push_back(Args.MakeArgString("-lm"));
if (Triple.isOSLinux())
CmdArgs.push_back(Args.MakeArgString("--pop-state"));
addArchSpecificRPath(TC, Args, CmdArgs);
diff --git a/clang/test/Driver/fveclib.c b/clang/test/Driver/fveclib.c
index 7d0985c4dd4f4..62361f4679cc6 100644
--- a/clang/test/Driver/fveclib.c
+++ b/clang/test/Driver/fveclib.c
@@ -116,11 +116,17 @@
/// Verify that vectorized routines library is being linked in.
// RUN: %clang -### --target=aarch64-pc-windows-msvc -fveclib=ArmPL %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-MSVC %s
// RUN: %clang -### --target=aarch64-linux-gnu -fveclib=ArmPL %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-LINUX %s
+// RUN: %clang -### --target=aarch64-linux-gnu -fveclib=ArmPL %s -nostdlib 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-NOSTDLIB-LINUX %s
// RUN: %clang -### --target=aarch64-linux-gnu -fveclib=ArmPL %s -lamath 2>&1 | FileCheck --check-prefix=CHECK-LINKING-AMATH-BEFORE-ARMPL-LINUX %s
// RUN: %clang -### --target=arm64-apple-darwin -fveclib=ArmPL %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-DARWIN %s
+// RUN: %clang -### --target=arm64-apple-darwin -fveclib=ArmPL -nostdlib %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-NOSTDLIB-DARWIN %s
// RUN: %clang -### --target=arm64-apple-darwin -fveclib=ArmPL %s -lamath 2>&1 | FileCheck --check-prefix=CHECK-LINKING-AMATH-BEFORE-ARMPL-DARWIN %s
// CHECK-LINKING-ARMPL-LINUX: "--push-state" "--as-needed" "-lm" "-lamath" "-lm" "--pop-state"
+// CHECK-LINKING-ARMPL-NOSTDLIB-LINUX: "--push-state" "--as-needed" "-lamath" "--pop-state"
+// CHECK-LINKING-ARMPL-NOSTDLIB-LINUX-NO: "-lm"
// CHECK-LINKING-ARMPL-DARWIN: "-lm" "-lamath" "-lm"
+// CHECK-LINKING-ARMPL-NOSTDLIB-DARWIN: "-lamath"
+// CHECK-LINKING-ARMPL-NOSTDLIB-DARWIN-NO: "-lm"
// CHECK-LINKING-ARMPL-MSVC: "--dependent-lib=amath"
// CHECK-LINKING-AMATH-BEFORE-ARMPL-LINUX: "-lamath" {{.*}}"--push-state" "--as-needed" "-lm" "-lamath" "-lm" "--pop-state"
// CHECK-LINKING-AMATH-BEFORE-ARMPL-DARWIN: "-lamath" {{.*}}"-lm" "-lamath" "-lm"
diff --git a/flang/test/Driver/fveclib.f90 b/flang/test/Driver/fveclib.f90
index 490ce974724a6..2539e07270a85 100644
--- a/flang/test/Driver/fveclib.f90
+++ b/flang/test/Driver/fveclib.f90
@@ -33,11 +33,17 @@
! RUN: %flang -### --target=aarch64-pc-windows-msvc -fveclib=ArmPL %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-MSVC %s
! RUN: %flang -### --target=aarch64-linux-gnu -fveclib=ArmPL %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-LINUX %s
+! RUN: %flang -### --target=aarch64-linux-gnu -fveclib=ArmPL -nostdlib %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-NOSTDLIB-LINUX %s
! RUN: %flang -### --target=aarch64-linux-gnu -fveclib=ArmPL %s -lamath 2>&1 | FileCheck --check-prefix=CHECK-LINKING-AMATH-BEFORE-ARMPL-LINUX %s
! RUN: %flang -### --target=arm64-apple-darwin -fveclib=ArmPL %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-DARWIN %s
+! RUN: %flang -### --target=arm64-apple-darwin -fveclib=ArmPL -nostdlib %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-NOSTDLIB-DARWIN %s
! RUN: %flang -### --target=arm64-apple-darwin -fveclib=ArmPL %s -lamath 2>&1 | FileCheck --check-prefix=CHECK-LINKING-AMATH-BEFORE-ARMPL-DARWIN %s
! CHECK-LINKING-ARMPL-LINUX: "--push-state" "--as-needed" "-lm" "-lamath" "-lm" "--pop-state"
+! CHECK-LINKING-ARMPL-NOSTDLIB-LINUX: "--push-state" "--as-needed" "-lamath" "--pop-state"
+! CHECK-LINKING-ARMPL-NOSTDLIB-LINUX-NO: "-lm"
! CHECK-LINKING-ARMPL-DARWIN: "-lm" "-lamath" "-lm"
+! CHECK-LINKING-ARMPL-NOSTDLIB-DARWIN: "-lamath"
+! CHECK-LINKING-ARMPL-NOSTDLIB-DARWIN-NO: "-lm"
! CHECK-LINKING-ARMPL-MSVC: "--dependent-lib=amath"
! CHECK-LINKING-AMATH-BEFORE-ARMPL-LINUX: "-lamath" {{.*}}"--push-state" "--as-needed" "-lm" "-lamath" "-lm" "--pop-state"
! CHECK-LINKING-AMATH-BEFORE-ARMPL-DARWIN: "-lamath" {{.*}}"-lm" "-lamath" "-lm"
|
|
@llvm/pr-subscribers-flang-driver Author: Paul Osmialowski (pawosm-arm) ChangesAlthough combining -fveclib=ArmPL with -nostdlib is a rare situation, it should still be supported correctly and should effect in avoidance of linking against libm. Full diff: https://github.com/llvm/llvm-project/pull/133578.diff 3 Files Affected:
diff --git a/clang/lib/Driver/ToolChains/CommonArgs.cpp b/clang/lib/Driver/ToolChains/CommonArgs.cpp
index 41cfa3d2e4f8c..5aac20e1cdf44 100644
--- a/clang/lib/Driver/ToolChains/CommonArgs.cpp
+++ b/clang/lib/Driver/ToolChains/CommonArgs.cpp
@@ -515,7 +515,7 @@ void tools::AddLinkerInputs(const ToolChain &TC, const InputInfoList &Inputs,
//
// 1. On Linux, link only when actually needed.
//
- // 2. Prefer libm functions over libamath.
+ // 2. Prefer libm functions over libamath (when no -nostdlib in use).
//
// 3. Link against libm to resolve libamath dependencies.
//
@@ -523,9 +523,11 @@ void tools::AddLinkerInputs(const ToolChain &TC, const InputInfoList &Inputs,
CmdArgs.push_back(Args.MakeArgString("--push-state"));
CmdArgs.push_back(Args.MakeArgString("--as-needed"));
}
- CmdArgs.push_back(Args.MakeArgString("-lm"));
+ if (!Args.hasArg(options::OPT_nostdlib))
+ CmdArgs.push_back(Args.MakeArgString("-lm"));
CmdArgs.push_back(Args.MakeArgString("-lamath"));
- CmdArgs.push_back(Args.MakeArgString("-lm"));
+ if (!Args.hasArg(options::OPT_nostdlib))
+ CmdArgs.push_back(Args.MakeArgString("-lm"));
if (Triple.isOSLinux())
CmdArgs.push_back(Args.MakeArgString("--pop-state"));
addArchSpecificRPath(TC, Args, CmdArgs);
diff --git a/clang/test/Driver/fveclib.c b/clang/test/Driver/fveclib.c
index 7d0985c4dd4f4..62361f4679cc6 100644
--- a/clang/test/Driver/fveclib.c
+++ b/clang/test/Driver/fveclib.c
@@ -116,11 +116,17 @@
/// Verify that vectorized routines library is being linked in.
// RUN: %clang -### --target=aarch64-pc-windows-msvc -fveclib=ArmPL %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-MSVC %s
// RUN: %clang -### --target=aarch64-linux-gnu -fveclib=ArmPL %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-LINUX %s
+// RUN: %clang -### --target=aarch64-linux-gnu -fveclib=ArmPL %s -nostdlib 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-NOSTDLIB-LINUX %s
// RUN: %clang -### --target=aarch64-linux-gnu -fveclib=ArmPL %s -lamath 2>&1 | FileCheck --check-prefix=CHECK-LINKING-AMATH-BEFORE-ARMPL-LINUX %s
// RUN: %clang -### --target=arm64-apple-darwin -fveclib=ArmPL %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-DARWIN %s
+// RUN: %clang -### --target=arm64-apple-darwin -fveclib=ArmPL -nostdlib %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-NOSTDLIB-DARWIN %s
// RUN: %clang -### --target=arm64-apple-darwin -fveclib=ArmPL %s -lamath 2>&1 | FileCheck --check-prefix=CHECK-LINKING-AMATH-BEFORE-ARMPL-DARWIN %s
// CHECK-LINKING-ARMPL-LINUX: "--push-state" "--as-needed" "-lm" "-lamath" "-lm" "--pop-state"
+// CHECK-LINKING-ARMPL-NOSTDLIB-LINUX: "--push-state" "--as-needed" "-lamath" "--pop-state"
+// CHECK-LINKING-ARMPL-NOSTDLIB-LINUX-NO: "-lm"
// CHECK-LINKING-ARMPL-DARWIN: "-lm" "-lamath" "-lm"
+// CHECK-LINKING-ARMPL-NOSTDLIB-DARWIN: "-lamath"
+// CHECK-LINKING-ARMPL-NOSTDLIB-DARWIN-NO: "-lm"
// CHECK-LINKING-ARMPL-MSVC: "--dependent-lib=amath"
// CHECK-LINKING-AMATH-BEFORE-ARMPL-LINUX: "-lamath" {{.*}}"--push-state" "--as-needed" "-lm" "-lamath" "-lm" "--pop-state"
// CHECK-LINKING-AMATH-BEFORE-ARMPL-DARWIN: "-lamath" {{.*}}"-lm" "-lamath" "-lm"
diff --git a/flang/test/Driver/fveclib.f90 b/flang/test/Driver/fveclib.f90
index 490ce974724a6..2539e07270a85 100644
--- a/flang/test/Driver/fveclib.f90
+++ b/flang/test/Driver/fveclib.f90
@@ -33,11 +33,17 @@
! RUN: %flang -### --target=aarch64-pc-windows-msvc -fveclib=ArmPL %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-MSVC %s
! RUN: %flang -### --target=aarch64-linux-gnu -fveclib=ArmPL %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-LINUX %s
+! RUN: %flang -### --target=aarch64-linux-gnu -fveclib=ArmPL -nostdlib %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-NOSTDLIB-LINUX %s
! RUN: %flang -### --target=aarch64-linux-gnu -fveclib=ArmPL %s -lamath 2>&1 | FileCheck --check-prefix=CHECK-LINKING-AMATH-BEFORE-ARMPL-LINUX %s
! RUN: %flang -### --target=arm64-apple-darwin -fveclib=ArmPL %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-DARWIN %s
+! RUN: %flang -### --target=arm64-apple-darwin -fveclib=ArmPL -nostdlib %s 2>&1 | FileCheck --check-prefix=CHECK-LINKING-ARMPL-NOSTDLIB-DARWIN %s
! RUN: %flang -### --target=arm64-apple-darwin -fveclib=ArmPL %s -lamath 2>&1 | FileCheck --check-prefix=CHECK-LINKING-AMATH-BEFORE-ARMPL-DARWIN %s
! CHECK-LINKING-ARMPL-LINUX: "--push-state" "--as-needed" "-lm" "-lamath" "-lm" "--pop-state"
+! CHECK-LINKING-ARMPL-NOSTDLIB-LINUX: "--push-state" "--as-needed" "-lamath" "--pop-state"
+! CHECK-LINKING-ARMPL-NOSTDLIB-LINUX-NO: "-lm"
! CHECK-LINKING-ARMPL-DARWIN: "-lm" "-lamath" "-lm"
+! CHECK-LINKING-ARMPL-NOSTDLIB-DARWIN: "-lamath"
+! CHECK-LINKING-ARMPL-NOSTDLIB-DARWIN-NO: "-lm"
! CHECK-LINKING-ARMPL-MSVC: "--dependent-lib=amath"
! CHECK-LINKING-AMATH-BEFORE-ARMPL-LINUX: "-lamath" {{.*}}"--push-state" "--as-needed" "-lm" "-lamath" "-lm" "--pop-state"
! CHECK-LINKING-AMATH-BEFORE-ARMPL-DARWIN: "-lamath" {{.*}}"-lm" "-lamath" "-lm"
|
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Seriously, this is something CI people signaled to me. Our CI builds everything with |
jhuber6
reviewed
Mar 31, 2025
| // | ||
| // 3. Link against libm to resolve libamath dependencies. | ||
| // | ||
| if (Triple.isOSLinux()) { | ||
| CmdArgs.push_back(Args.MakeArgString("--push-state")); | ||
| CmdArgs.push_back(Args.MakeArgString("--as-needed")); | ||
| } | ||
| CmdArgs.push_back(Args.MakeArgString("-lm")); | ||
| if (!Args.hasArg(options::OPT_nostdlib)) | ||
| CmdArgs.push_back(Args.MakeArgString("-lm")); | ||
| CmdArgs.push_back(Args.MakeArgString("-lamath")); |
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Why is this still passed? Normally nostdlib implies turning off all implicitly linked standard libraries.
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There was a very long story behind this which has been discussed while this code has been introduced. In short: libamath replaces some of the libm functions, but at the same time, some of the libamath functions depend on libm. In this case, we don't want to outshadow libm (we only want to provide vector implementations on as-needed basis), and at the same time we want to produce a valid binary with no missing symbols (and that's wehre libm is needed) as long as no -nostdlib flag is given.
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I guess -fvevlib can be seen as an explicit request for libraries, so I can see it.
jhuber6
reviewed
Mar 31, 2025
| // | ||
| // 3. Link against libm to resolve libamath dependencies. | ||
| // | ||
| if (Triple.isOSLinux()) { | ||
| CmdArgs.push_back(Args.MakeArgString("--push-state")); | ||
| CmdArgs.push_back(Args.MakeArgString("--as-needed")); | ||
| } | ||
| CmdArgs.push_back(Args.MakeArgString("-lm")); | ||
| if (!Args.hasArg(options::OPT_nostdlib)) | ||
| CmdArgs.push_back(Args.MakeArgString("-lm")); | ||
| CmdArgs.push_back(Args.MakeArgString("-lamath")); |
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I guess -fvevlib can be seen as an explicit request for libraries, so I can see it.
clang/test/Driver/fveclib.c
Outdated
| // CHECK-LINKING-ARMPL-DARWIN: "-lm" "-lamath" "-lm" | ||
| // CHECK-LINKING-ARMPL-NOSTDLIB-DARWIN: "-lamath" | ||
| // CHECK-LINKING-ARMPL-NOSTDLIB-DARWIN-NO: "-lm" |
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Does this work? I thought it was -NOT, but because they do the same thing.
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Well it passes all of the tests so I can assume it does. And I've just found more files where -NO: and -NOT: is being used both in the same file, e.g. pragma-attribute-strict-subjects.c or warn-unsafe-buffer-usage-fixits-pointer-access.cpp. But generally, I should follow whatever convention I've encountered, so I'd change it to NOT:, as it has been used in this file arleady, and the FileCheck page says about NOT: but nothing about NO:.
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Pushed a correction. It still passes here locally.
…against libm Although combining -fveclib=ArmPL with -nostdlib is a rare situation, it should still be supported correctly and should effect in avoidance of linking against libm.
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jhuber6
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Mar 31, 2025
This is all due to the way libamath incremetnally emerged into its present existence. And yes, static linking added another layer of problems here. |
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Although combining -fveclib=ArmPL with -nostdlib is a rare situation, it should still be supported correctly and should effect in avoidance of linking against libm.