https://github.com/amy-kwan created
https://github.com/llvm/llvm-project/pull/79252
This patch disallows the use of the -maix-small-local-exec-tls and
-fno-data-sections options within clang, and also disallows the use of the
aix-small-local-exec-tls attribute with the -data-sections=false option in llc.
This is because having data sections off when using the
aix-small-local-exec-tls feature is not ideal for performance. As the
small-local-exec-tls region is a limited resource, this space should not used
for variables that may be replaced.
Note, that on AIX, data sections is turned on by default, so this patch makes
it so that a diagnostic is emitted when users explicitly turn off data sections
while using the aix-small-local-exec-tls feature.
>From c6fb2a4e1bc329bbebe930feebf462fa0d502df0 Mon Sep 17 00:00:00 2001
From: Amy Kwan <amy.kw...@ibm.com>
Date: Tue, 23 Jan 2024 22:19:49 -0600
Subject: [PATCH] [AIX][TLS] Disallow the use of -maix-small-local-exec-tls and
-fno-data-sections
This patch disallows the use of the -maix-small-local-exec-tls and
-fno-data-sections options within clang, and also disallows the use of the
aix-small-local-exec-tls attribute with the -data-sections=false option in llc.
This is because having data sections off when using the aix-small-local-exec-tls
feature is not ideal for performance. As the small-local-exec-tls region is a
limited resource, this space should not used for variables that may be replaced.
Note, that on AIX, data sections is turned on by default, so this patch makes it
so that a diagnostic is emitted when users explicitly turn off data sections
while using the aix-small-local-exec-tls feature.
---
clang/lib/Basic/Targets/PPC.cpp | 8 -------
clang/lib/Driver/ToolChains/Arch/PPC.cpp | 19 +++++++++++++++++
clang/test/Driver/aix-small-local-exec-tls.c | 7 +++++++
llvm/lib/Target/PowerPC/PPCSubtarget.cpp | 21 +++++++++++++++----
...ix-small-local-exec-tls-opt-IRattribute.ll | 7 +++++++
5 files changed, 50 insertions(+), 12 deletions(-)
diff --git a/clang/lib/Basic/Targets/PPC.cpp b/clang/lib/Basic/Targets/PPC.cpp
index 41935abfb65d3b9..911b80c98f7ad62 100644
--- a/clang/lib/Basic/Targets/PPC.cpp
+++ b/clang/lib/Basic/Targets/PPC.cpp
@@ -646,14 +646,6 @@ bool PPCTargetInfo::initFeatureMap(
return false;
}
- if (llvm::is_contained(FeaturesVec, "+aix-small-local-exec-tls")) {
- if (!getTriple().isOSAIX() || !getTriple().isArch64Bit()) {
- Diags.Report(diag::err_opt_not_valid_on_target)
- << "-maix-small-local-exec-tls";
- return false;
- }
- }
-
return TargetInfo::initFeatureMap(Features, Diags, CPU, FeaturesVec);
}
diff --git a/clang/lib/Driver/ToolChains/Arch/PPC.cpp
b/clang/lib/Driver/ToolChains/Arch/PPC.cpp
index ab24d14992cd7a1..5ffe73236205d3b 100644
--- a/clang/lib/Driver/ToolChains/Arch/PPC.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/PPC.cpp
@@ -122,6 +122,25 @@ void ppc::getPPCTargetFeatures(const Driver &D, const
llvm::Triple &Triple,
ppc::ReadGOTPtrMode ReadGOT = ppc::getPPCReadGOTPtrMode(D, Triple, Args);
if (ReadGOT == ppc::ReadGOTPtrMode::SecurePlt)
Features.push_back("+secure-plt");
+
+ bool UseSeparateSections = isUseSeparateSections(Triple);
+ bool HasDefaultDataSections = Triple.isOSBinFormatXCOFF();
+ if (Args.hasArg(options::OPT_maix_small_local_exec_tls)) {
+ if (!Triple.isOSAIX() || !Triple.isArch64Bit())
+ D.Diag(diag::err_opt_not_valid_on_target) <<
"-maix-small-local-exec-tls";
+
+ // The -maix-small-local-exec-tls option should only be used with
+ // -fdata-sections, as having data sections turned off with this option
+ // is not ideal for performance. Moreover, the small-local-exec-tls region
+ // is a limited resource, and should not be used for variables that may
+ // be replaced.
+ if (!Args.hasFlag(options::OPT_fdata_sections,
+ options::OPT_fno_data_sections,
+ UseSeparateSections || HasDefaultDataSections))
+ D.Diag(diag::err_drv_argument_only_allowed_with)
+ << "-maix-small-local-exec-tls"
+ << "-fdata-sections";
+ }
}
ppc::ReadGOTPtrMode ppc::getPPCReadGOTPtrMode(const Driver &D, const
llvm::Triple &Triple,
diff --git a/clang/test/Driver/aix-small-local-exec-tls.c
b/clang/test/Driver/aix-small-local-exec-tls.c
index 7a2eec6989eef89..e6719502a3babc3 100644
--- a/clang/test/Driver/aix-small-local-exec-tls.c
+++ b/clang/test/Driver/aix-small-local-exec-tls.c
@@ -12,6 +12,12 @@
// RUN: -fsyntax-only %s 2>&1 | FileCheck
--check-prefix=CHECK-UNSUPPORTED-LINUX %s
// RUN: not %clang -target powerpc64-unknown-linux-gnu
-maix-small-local-exec-tls \
// RUN: -fsyntax-only %s 2>&1 | FileCheck
--check-prefix=CHECK-UNSUPPORTED-LINUX %s
+// RUN: not %clang -target powerpc64-unknown-aix -maix-small-local-exec-tls \
+// RUN: -fsyntax-only -fno-data-sections %s 2>&1 | \
+// RUN: FileCheck --check-prefix=CHECK-UNSUPPORTED-NO-DATASEC %s
+// RUN: not %clang -target powerpc64-unknown-linux-gnu
-maix-small-local-exec-tls \
+// RUN: -fsyntax-only -fno-data-sections %s 2>&1 | \
+// RUN: FileCheck --check-prefix=CHECK-UNSUPPORTED-NO-DATASEC %s
int test(void) {
return 0;
@@ -23,6 +29,7 @@ int test(void) {
// CHECK-UNSUPPORTED-AIX32: option '-maix-small-local-exec-tls' cannot be
specified on this target
// CHECK-UNSUPPORTED-LINUX: option '-maix-small-local-exec-tls' cannot be
specified on this target
+// CHECK-UNSUPPORTED-NO-DATASEC: invalid argument '-maix-small-local-exec-tls'
only allowed with '-fdata-sections'
// CHECK-AIX_SMALL_LOCALEXEC_TLS: test() #0 {
// CHECK-AIX_SMALL_LOCALEXEC_TLS: attributes #0 = {
diff --git a/llvm/lib/Target/PowerPC/PPCSubtarget.cpp
b/llvm/lib/Target/PowerPC/PPCSubtarget.cpp
index c9740818c9bfd6f..2735bdee3bcfcc1 100644
--- a/llvm/lib/Target/PowerPC/PPCSubtarget.cpp
+++ b/llvm/lib/Target/PowerPC/PPCSubtarget.cpp
@@ -124,10 +124,23 @@ void PPCSubtarget::initSubtargetFeatures(StringRef CPU,
StringRef TuneCPU,
// Determine endianness.
IsLittleEndian = TM.isLittleEndian();
- if (HasAIXSmallLocalExecTLS && (!TargetTriple.isOSAIX() || !IsPPC64))
- report_fatal_error(
- "The aix-small-local-exec-tls attribute is only supported on AIX in "
- "64-bit mode.\n", false);
+ if (HasAIXSmallLocalExecTLS) {
+ if (!TargetTriple.isOSAIX() || !IsPPC64)
+ report_fatal_error(
+ "The aix-small-local-exec-tls attribute is only supported on AIX in "
+ "64-bit mode.\n",
+ false);
+ // The aix-small-local-exec-tls attribute should only be used with
+ // -data-sections, as having data sections turned off with this option
+ // is not ideal for performance. Moreover, the small-local-exec-tls region
+ // is a limited resource, and should not be used for variables that may
+ // be replaced.
+ if (!TM.getDataSections())
+ report_fatal_error(
+ "The aix-small-local-exec-tls attribute can only be specified with "
+ "-data-sections.\n",
+ false);
+ }
}
bool PPCSubtarget::enableMachineScheduler() const { return true; }
diff --git
a/llvm/test/CodeGen/PowerPC/check-aix-small-local-exec-tls-opt-IRattribute.ll
b/llvm/test/CodeGen/PowerPC/check-aix-small-local-exec-tls-opt-IRattribute.ll
index 62ec0974b0eb55d..00f58ecda15fe1f 100644
---
a/llvm/test/CodeGen/PowerPC/check-aix-small-local-exec-tls-opt-IRattribute.ll
+++
b/llvm/test/CodeGen/PowerPC/check-aix-small-local-exec-tls-opt-IRattribute.ll
@@ -4,6 +4,9 @@
; RUN: < %s 2>&1 | FileCheck %s --check-prefix=CHECK-NOT-SUPPORTED
; RUN: not llc -mtriple powerpc64le-unknown-linux-gnu -ppc-asm-full-reg-names \
; RUN: < %s 2>&1 | FileCheck %s --check-prefix=CHECK-NOT-SUPPORTED
+; RUN: not llc -mtriple powerpc64-ibm-aix-xcoff -ppc-asm-full-reg-names \
+; RUN: -data-sections=false < %s 2>&1 | \
+; RUN: FileCheck %s --check-prefix=CHECK-NOT-SUPPORTED-NO-DATASEC
define dso_local signext i32 @testWithIRAttr() #0 {
entry:
@@ -12,6 +15,10 @@ entry:
; Check that the aix-small-local-exec-tls attribute is not supported on Linux
and AIX (32-bit).
; CHECK-NOT-SUPPORTED: The aix-small-local-exec-tls attribute is only
supported on AIX in 64-bit mode.
+; Check that the aix-small-local-exec-tls attribute is only supported when
+; data sections are enabled.
+; CHECK-NOT-SUPPORTED-NO-DATASEC: The aix-small-local-exec-tls attribute can
only be specified with -data-sections.
+
; Make sure that the test was actually compiled successfully after using the
; aix-small-local-exec-tls attribute.
; CHECK-LABEL: testWithIRAttr:
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