[clang] c38efb4 - [clang] Implement -falign-loops=N (N is a power of 2) for non-LTO
Fangrui Song via cfe-commits
cfe-commits at lists.llvm.org
Thu Aug 5 12:17:56 PDT 2021
Author: Fangrui Song
Date: 2021-08-05T12:17:50-07:00
New Revision: c38efb4899eac7b82daaf1320ad79f6271f9648a
URL: https://github.com/llvm/llvm-project/commit/c38efb4899eac7b82daaf1320ad79f6271f9648a
DIFF: https://github.com/llvm/llvm-project/commit/c38efb4899eac7b82daaf1320ad79f6271f9648a.diff
LOG: [clang] Implement -falign-loops=N (N is a power of 2) for non-LTO
GCC supports multiple forms of -falign-loops=.
-falign-loops= is currently ignored in Clang.
This patch implements the simplest but the most useful form where N is a
power of 2.
The underlying implementation uses a `llvm::TargetOptions` option for now.
Bitcode generation ignores this option.
Differential Revision: https://reviews.llvm.org/D106701
Added:
clang/test/CodeGen/align-loops.c
clang/test/Driver/falign-loops.c
Modified:
clang/include/clang/Basic/CodeGenOptions.def
clang/include/clang/Basic/DiagnosticDriverKinds.td
clang/include/clang/Basic/LangOptions.def
clang/include/clang/Driver/Options.td
clang/lib/CodeGen/BackendUtil.cpp
clang/lib/Driver/ToolChains/Clang.cpp
clang/test/Driver/clang_f_opts.c
Removed:
################################################################################
diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def
index e3202cf887561..73edae63bfc91 100644
--- a/clang/include/clang/Basic/CodeGenOptions.def
+++ b/clang/include/clang/Basic/CodeGenOptions.def
@@ -293,6 +293,8 @@ CODEGENOPT(StackRealignment , 1, 0) ///< Control whether to force stack
///< realignment.
CODEGENOPT(UseInitArray , 1, 0) ///< Control whether to use .init_array or
///< .ctors.
+VALUE_CODEGENOPT(LoopAlignment , 32, 0) ///< Overrides default loop
+ ///< alignment, if not 0.
VALUE_CODEGENOPT(StackAlignment , 32, 0) ///< Overrides default stack
///< alignment, if not 0.
VALUE_CODEGENOPT(StackProbeSize , 32, 4096) ///< Overrides default stack
diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
index 78d7ba6b63836..660f7e418b9ea 100644
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -228,6 +228,7 @@ def err_drv_invalid_value : Error<"invalid value '%1' in '%0'">;
def err_drv_invalid_int_value : Error<"invalid integral value '%1' in '%0'">;
def err_drv_invalid_value_with_suggestion : Error<
"invalid value '%1' in '%0', expected one of: %2">;
+def err_drv_alignment_not_power_of_two : Error<"alignment is not a power of 2 in '%0'">;
def err_drv_invalid_remap_file : Error<
"invalid option '%0' not of the form <from-file>;<to-file>">;
def err_drv_invalid_gcc_output_type : Error<
diff --git a/clang/include/clang/Basic/LangOptions.def b/clang/include/clang/Basic/LangOptions.def
index 4a91e2c20dc58..7549ad43911be 100644
--- a/clang/include/clang/Basic/LangOptions.def
+++ b/clang/include/clang/Basic/LangOptions.def
@@ -399,6 +399,7 @@ ENUM_LANGOPT(ClangABICompat, ClangABI, 4, ClangABI::Latest,
"with")
COMPATIBLE_VALUE_LANGOPT(FunctionAlignment, 5, 0, "Default alignment for functions")
+COMPATIBLE_VALUE_LANGOPT(LoopAlignment, 32, 0, "Default alignment for loops")
LANGOPT(FixedPoint, 1, 0, "fixed point types")
LANGOPT(PaddingOnUnsignedFixedPoint, 1, 0,
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 9f42072a92900..79f541f6b2473 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -1087,6 +1087,9 @@ defm access_control : BoolFOption<"access-control",
PosFlag<SetTrue>>;
def falign_functions : Flag<["-"], "falign-functions">, Group<f_Group>;
def falign_functions_EQ : Joined<["-"], "falign-functions=">, Group<f_Group>;
+def falign_loops_EQ : Joined<["-"], "falign-loops=">, Group<f_Group>, Flags<[CC1Option]>, MetaVarName<"<N>">,
+ HelpText<"N must be a power of two. Align loops to the boundary">,
+ MarshallingInfoInt<CodeGenOpts<"LoopAlignment">>;
def fno_align_functions: Flag<["-"], "fno-align-functions">, Group<f_Group>;
defm allow_editor_placeholders : BoolFOption<"allow-editor-placeholders",
LangOpts<"AllowEditorPlaceholders">, DefaultFalse,
@@ -4336,7 +4339,6 @@ def ld_path_EQ : Joined<["--"], "ld-path=">, Group<Link_Group>;
defm align_labels : BooleanFFlag<"align-labels">, Group<clang_ignored_gcc_optimization_f_Group>;
def falign_labels_EQ : Joined<["-"], "falign-labels=">, Group<clang_ignored_gcc_optimization_f_Group>;
defm align_loops : BooleanFFlag<"align-loops">, Group<clang_ignored_gcc_optimization_f_Group>;
-def falign_loops_EQ : Joined<["-"], "falign-loops=">, Group<clang_ignored_gcc_optimization_f_Group>;
defm align_jumps : BooleanFFlag<"align-jumps">, Group<clang_ignored_gcc_optimization_f_Group>;
def falign_jumps_EQ : Joined<["-"], "falign-jumps=">, Group<clang_ignored_gcc_optimization_f_Group>;
diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index 0915255bf88f1..9e4e40a36e056 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -580,6 +580,7 @@ static bool initTargetOptions(DiagnosticsEngine &Diags,
Options.ValueTrackingVariableLocations =
CodeGenOpts.ValueTrackingVariableLocations;
Options.XRayOmitFunctionIndex = CodeGenOpts.XRayOmitFunctionIndex;
+ Options.LoopAlignment = CodeGenOpts.LoopAlignment;
Options.MCOptions.SplitDwarfFile = CodeGenOpts.SplitDwarfFile;
Options.MCOptions.MCRelaxAll = CodeGenOpts.RelaxAll;
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 3de54e248f248..1c79640be80f6 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -4739,6 +4739,22 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
CmdArgs.push_back(Args.MakeArgString(std::to_string(FunctionAlignment)));
}
+ // We support -falign-loops=N where N is a power of 2. GCC supports more
+ // forms.
+ if (const Arg *A = Args.getLastArg(options::OPT_falign_loops_EQ)) {
+ unsigned Value = 0;
+ if (StringRef(A->getValue()).getAsInteger(10, Value) || Value > 65536)
+ TC.getDriver().Diag(diag::err_drv_invalid_int_value)
+ << A->getAsString(Args) << A->getValue();
+ else if (Value & Value - 1)
+ TC.getDriver().Diag(diag::err_drv_alignment_not_power_of_two)
+ << A->getAsString(Args) << A->getValue();
+ // Treat =0 as unspecified (use the target preference).
+ if (Value)
+ CmdArgs.push_back(Args.MakeArgString("-falign-loops=" +
+ Twine(std::min(Value, 65536u))));
+ }
+
llvm::Reloc::Model RelocationModel;
unsigned PICLevel;
bool IsPIE;
diff --git a/clang/test/CodeGen/align-loops.c b/clang/test/CodeGen/align-loops.c
new file mode 100644
index 0000000000000..a42c8be818755
--- /dev/null
+++ b/clang/test/CodeGen/align-loops.c
@@ -0,0 +1,15 @@
+// REQUIRES: x86-registered-target
+/// Check asm because we use llvm::TargetOptions.
+
+// RUN: %clang_cc1 -triple=x86_64 -S %s -falign-loops=8 -O -o - | FileCheck %s --check-prefixes=CHECK,CHECK_8
+// RUN: %clang_cc1 -triple=x86_64 -S %s -falign-loops=32 -O -o - | FileCheck %s --check-prefixes=CHECK,CHECK_32
+
+// CHECK-LABEL: foo:
+// CHECK_8: .p2align 3, 0x90
+// CHECK_32: .p2align 5, 0x90
+
+void bar();
+void foo() {
+ for (int i = 0; i < 64; ++i)
+ bar();
+}
diff --git a/clang/test/Driver/clang_f_opts.c b/clang/test/Driver/clang_f_opts.c
index 979ab4e4299f8..487ae08250396 100644
--- a/clang/test/Driver/clang_f_opts.c
+++ b/clang/test/Driver/clang_f_opts.c
@@ -397,7 +397,6 @@
// CHECK-WARNING-DAG: optimization flag '-falign-labels' is not supported
// CHECK-WARNING-DAG: optimization flag '-falign-labels=100' is not supported
// CHECK-WARNING-DAG: optimization flag '-falign-loops' is not supported
-// CHECK-WARNING-DAG: optimization flag '-falign-loops=100' is not supported
// CHECK-WARNING-DAG: optimization flag '-falign-jumps' is not supported
// CHECK-WARNING-DAG: optimization flag '-falign-jumps=100' is not supported
// CHECK-WARNING-DAG: optimization flag '-fexcess-precision=100' is not supported
diff --git a/clang/test/Driver/falign-loops.c b/clang/test/Driver/falign-loops.c
new file mode 100644
index 0000000000000..30a9ae9637d2e
--- /dev/null
+++ b/clang/test/Driver/falign-loops.c
@@ -0,0 +1,17 @@
+/// Treat -falign-loops=0 as not specifying the option.
+// RUN: %clang -### -falign-loops=0 %s 2>&1 | FileCheck %s --check-prefix=CHECK_NO
+// RUN: %clang -### -falign-loops=1 %s 2>&1 | FileCheck %s --check-prefix=CHECK_1
+// RUN: %clang -### -falign-loops=4 %s 2>&1 | FileCheck %s --check-prefix=CHECK_4
+/// Only powers of 2 are supported for now.
+// RUN: %clang -### -falign-loops=5 %s 2>&1 | FileCheck %s --check-prefix=CHECK_5
+// RUN: %clang -### -falign-loops=65536 %s 2>&1 | FileCheck %s --check-prefix=CHECK_65536
+// RUN: %clang -### -falign-loops=65537 %s 2>&1 | FileCheck %s --check-prefix=CHECK_65537
+// RUN: %clang -### -falign-loops=a %s 2>&1 | FileCheck %s --check-prefix=CHECK_ERR_A
+
+// CHECK_NO-NOT: "-falign-loops=
+// CHECK_1: "-falign-loops=1"
+// CHECK_4: "-falign-loops=4"
+// CHECK_5: error: alignment is not a power of 2 in '-falign-loops=5'
+// CHECK_65536: "-falign-loops=65536"
+// CHECK_65537: error: invalid integral value '65537' in '-falign-loops=65537'
+// CHECK_ERR_A: error: invalid integral value 'a' in '-falign-loops=a'
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