[clang] 792b109 - [Driver][X86] Add -mpad-max-prefix-size
Shengchen Kan via cfe-commits
cfe-commits at lists.llvm.org
Thu Apr 9 04:34:34 PDT 2020
Author: Shengchen Kan
Date: 2020-04-09T19:34:12+08:00
New Revision: 792b10978dfdd424721fbf0ffd99c35d628f2321
URL: https://github.com/llvm/llvm-project/commit/792b10978dfdd424721fbf0ffd99c35d628f2321
DIFF: https://github.com/llvm/llvm-project/commit/792b10978dfdd424721fbf0ffd99c35d628f2321.diff
LOG: [Driver][X86] Add -mpad-max-prefix-size
Summary:
The option `-mpad-max-prefix-size` performs some checking and delegate to MC option `-x86-pad-max-prefix-size`. This option is designed for eliminate NOPs when we need to align something by adding redundant prefixes to instructions, e.g. it can be used along with `-malign-branch`, `-malign-branch-boundary` to prefix padding branch.
It has similar (but slightly different) effect as GAS's option `-malign-branch-prefix-size`, e.g. `-mpad-max-prefix-size` can also elminate NOPs emitted by align directive, so we use a different name here. I remove the option `-malign-branch-prefix-size` since is unimplemented and not needed. If we need to be compatible with GAS, we can make `-malign-branch-prefix-size` an alias for this option later.
Reviewers: jyknight, reames, MaskRay, craig.topper, LuoYuanke
Reviewed By: MaskRay, LuoYuanke
Subscribers: annita.zhang, cfe-commits
Tags: #clang
Differential Revision: https://reviews.llvm.org/D77628
Added:
Modified:
clang/include/clang/Driver/Options.td
clang/lib/Driver/ToolChains/Clang.cpp
clang/test/Driver/x86-malign-branch.c
clang/test/Driver/x86-malign-branch.s
Removed:
################################################################################
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index 430e7292757e..a395b680eb88 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -2187,7 +2187,8 @@ def malign_branch_EQ : CommaJoined<["-"], "malign-branch=">, Group<m_Group>, Fla
HelpText<"Specify types of branches to align">;
def malign_branch_boundary_EQ : Joined<["-"], "malign-branch-boundary=">, Group<m_Group>, Flags<[DriverOption]>,
HelpText<"Specify the boundary's size to align branches">;
-def malign_branch_prefix_size_EQ : Joined<["-"], "malign-branch-prefix-size=">, Group<m_Group>;
+def mpad_max_prefix_size_EQ : Joined<["-"], "mpad-max-prefix-size=">, Group<m_Group>, Flags<[DriverOption]>,
+ HelpText<"Specify maximum number of prefixes to use for padding">;
def mbranches_within_32B_boundaries : Flag<["-"], "mbranches-within-32B-boundaries">, Flags<[DriverOption]>, Group<m_Group>,
HelpText<"Align selected branches (fused, jcc, jmp) within 32-byte boundary">;
def mfancy_math_387 : Flag<["-"], "mfancy-math-387">, Group<clang_ignored_m_Group>;
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 2b368131f5cc..5f9b6d813416 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -2078,17 +2078,16 @@ static void addX86AlignBranchArgs(const Driver &D, const ArgList &Args,
CmdArgs.push_back("-mllvm");
CmdArgs.push_back(Args.MakeArgString("-x86-align-branch=" + AlignBranch));
}
- if (const Arg *A =
- Args.getLastArg(options::OPT_malign_branch_prefix_size_EQ)) {
+ if (const Arg *A = Args.getLastArg(options::OPT_mpad_max_prefix_size_EQ)) {
StringRef Value = A->getValue();
unsigned PrefixSize;
- if (Value.getAsInteger(10, PrefixSize) || PrefixSize > 5) {
+ if (Value.getAsInteger(10, PrefixSize)) {
D.Diag(diag::err_drv_invalid_argument_to_option)
<< Value << A->getOption().getName();
} else {
CmdArgs.push_back("-mllvm");
- CmdArgs.push_back(Args.MakeArgString("-x86-align-branch-prefix-size=" +
- Twine(PrefixSize)));
+ CmdArgs.push_back(
+ Args.MakeArgString("-x86-pad-max-prefix-size=" + Twine(PrefixSize)));
}
}
}
diff --git a/clang/test/Driver/x86-malign-branch.c b/clang/test/Driver/x86-malign-branch.c
index 6098caf0b5d4..5180eb0a1619 100644
--- a/clang/test/Driver/x86-malign-branch.c
+++ b/clang/test/Driver/x86-malign-branch.c
@@ -18,14 +18,11 @@
// TYPE-ERR: invalid argument 'foo' to -malign-branch=; each element must be one of: fused, jcc, jmp, call, ret, indirect
// TYPE-ERR: invalid argument 'bar' to -malign-branch=; each element must be one of: fused, jcc, jmp, call, ret, indirect
-/// Test -malign-branch-prefix-size=
-// RUN: %clang -target x86_64 -malign-branch-prefix-size=0 %s -c -### 2>&1 | FileCheck %s --check-prefix=PREFIX-0
-// PREFIX-0: "-mllvm" "-x86-align-branch-prefix-size=0"
-// RUN: %clang -target x86_64 -malign-branch-prefix-size=5 %s -c -### 2>&1 | FileCheck %s --check-prefix=PREFIX-5
-// PREFIX-5: "-mllvm" "-x86-align-branch-prefix-size=5"
-
-// RUN: %clang -target x86_64 -malign-branch-prefix-size=6 %s -c -### 2>&1 | FileCheck %s --check-prefix=PREFIX-6
-// PREFIX-6: invalid argument
+/// Test -mpad-max-prefix-size=
+// RUN: %clang -target x86_64 -mpad-max-prefix-size=0 %s -c -### 2>&1 | FileCheck %s --check-prefix=PREFIX-0
+// PREFIX-0: "-mllvm" "-x86-pad-max-prefix-size=0"
+// RUN: %clang -target x86_64 -mpad-max-prefix-size=15 %s -c -### 2>&1 | FileCheck %s --check-prefix=PREFIX-15
+// PREFIX-15: "-mllvm" "-x86-pad-max-prefix-size=15"
/// Test -mbranches-within-32B-boundaries
// RUN: %clang -target x86_64 -mbranches-within-32B-boundaries %s -c -### 2>&1 | FileCheck %s --check-prefix=32B
@@ -34,6 +31,6 @@
/// Unsupported on other targets.
// RUN: %clang -target aarch64 -malign-branch=jmp %s -c -### 2>&1 | FileCheck --check-prefix=UNUSED %s
// RUN: %clang -target aarch64 -malign-branch-boundary=7 %s -c -### 2>&1 | FileCheck --check-prefix=UNUSED %s
-// RUN: %clang -target aarch64 -malign-branch-prefix-size=15 %s -c -### 2>&1 | FileCheck --check-prefix=UNUSED %s
+// RUN: %clang -target aarch64 -mpad-max-prefix-size=15 %s -c -### 2>&1 | FileCheck --check-prefix=UNUSED %s
// RUN: %clang -target aarch64 -mbranches-within-32B-boundaries %s -c -### 2>&1 | FileCheck --check-prefix=UNUSED %s
// UNUSED: warning: argument unused
diff --git a/clang/test/Driver/x86-malign-branch.s b/clang/test/Driver/x86-malign-branch.s
index 280a84ea0c6e..049fabad7257 100644
--- a/clang/test/Driver/x86-malign-branch.s
+++ b/clang/test/Driver/x86-malign-branch.s
@@ -6,8 +6,8 @@
// RUN: %clang -target x86_64 -malign-branch=fused,jcc,jmp %s -c -### %s 2>&1 | FileCheck %s --check-prefix=TYPE
// TYPE: "-mllvm" "-x86-align-branch=fused+jcc+jmp"
-// RUN: %clang -target x86_64 -malign-branch-prefix-size=5 %s -c -### 2>&1 | FileCheck %s --check-prefix=PREFIX
-// PREFIX: "-mllvm" "-x86-align-branch-prefix-size=5"
+// RUN: %clang -target x86_64 -mpad-max-prefix-size=5 %s -c -### 2>&1 | FileCheck %s --check-prefix=PREFIX
+// PREFIX: "-mllvm" "-x86-pad-max-prefix-size=5"
// RUN: %clang -target x86_64 -mbranches-within-32B-boundaries %s -c -### 2>&1 | FileCheck %s --check-prefix=32B
// 32B: "-mllvm" "-x86-branches-within-32B-boundaries"
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