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When optimizing for size, enable loop rerolling by default 

We have a loop-rerolling optimization which can be enabled by using
-freroll-loops. While sometimes loops are hand-unrolled for performance
reasons, when optimizing for size, we should always undo this manual
optimization to produce smaller code (our optimizer's unroller will still
unroll the rerolled loops if it thinks that is a good idea).

llvm-svn: 283685
This commit is contained in:
Hal Finkel 2016-10-09 03:06:31 +00:00
parent 5b5f4f0c74
commit 60ebf61274
2 changed files with 15 additions and 1 deletions
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11
clang/lib/Driver/Tools.cpp
View File

@ -5227,9 +5227,18 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
}
if (Arg *A = Args.getLastArg(options::OPT_freroll_loops,
options::OPT_fno_reroll_loops))
options::OPT_fno_reroll_loops)) {
if (A->getOption().matches(options::OPT_freroll_loops))
CmdArgs.push_back("-freroll-loops");
} else if (Arg *A = Args.getLastArg(options::OPT_O_Group)) {
// If rerolling is not explicitly enabled or disabled, then enable when
// optimizing for size.
if (A->getOption().matches(options::OPT_O)) {
StringRef S(A->getValue());
if (S == "s" || S == "z")
CmdArgs.push_back("-freroll-loops");
}
}
Args.AddLastArg(CmdArgs, options::OPT_fwritable_strings);
Args.AddLastArg(CmdArgs, options::OPT_funroll_loops,

5
clang/test/Driver/clang_f_opts.c
View File

@ -47,7 +47,12 @@
// CHECK-NO-UNROLL-LOOPS: "-fno-unroll-loops"
// RUN: %clang -### -S -freroll-loops %s 2>&1 | FileCheck -check-prefix=CHECK-REROLL-LOOPS %s
// RUN: %clang -### -S -Os %s 2>&1 | FileCheck -check-prefix=CHECK-REROLL-LOOPS %s
// RUN: %clang -### -S -Oz %s 2>&1 | FileCheck -check-prefix=CHECK-REROLL-LOOPS %s
// RUN: %clang -### -S -fno-reroll-loops %s 2>&1 | FileCheck -check-prefix=CHECK-NO-REROLL-LOOPS %s
// RUN: %clang -### -S -Os -fno-reroll-loops %s 2>&1 | FileCheck -check-prefix=CHECK-NO-REROLL-LOOPS %s
// RUN: %clang -### -S -Oz -fno-reroll-loops %s 2>&1 | FileCheck -check-prefix=CHECK-NO-REROLL-LOOPS %s
// RUN: %clang -### -S -O1 %s 2>&1 | FileCheck -check-prefix=CHECK-NO-REROLL-LOOPS %s
// RUN: %clang -### -S -fno-reroll-loops -freroll-loops %s 2>&1 | FileCheck -check-prefix=CHECK-REROLL-LOOPS %s
// RUN: %clang -### -S -freroll-loops -fno-reroll-loops %s 2>&1 | FileCheck -check-prefix=CHECK-NO-REROLL-LOOPS %s
// CHECK-REROLL-LOOPS: "-freroll-loops"