Changes for ffs lib call simplification:
* Check for availability of ffsll call in configure script
* Support ffs, ffsl, and ffsll conversion to constant value if the argument
is constant.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22027 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index 093d9f1..becdb14 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -484,8 +484,8 @@
dnl===
dnl===-----------------------------------------------------------------------===
-AC_CHECK_FUNCS([backtrace getcwd getpagesize getrusage gettimeofday isatty ])
-AC_CHECK_FUNCS([mkdtemp mkstemp mktemp ])
+AC_CHECK_FUNCS([backtrace ffsll getcwd getpagesize getrusage gettimeofday ])
+AC_CHECK_FUNCS([isatty mkdtemp mkstemp mktemp ])
AC_CHECK_FUNCS([realpath sbrk setrlimit strdup strerror strerror_r ])
AC_CHECK_FUNCS([strtoll strtoq sysconf])
AC_C_PRINTF_A
diff --git a/configure b/configure
index 9485170..4948bc6 100755
--- a/configure
+++ b/configure
@@ -27227,7 +27227,7 @@
-for ac_func in backtrace getcwd getpagesize getrusage gettimeofday isatty
+for ac_func in backtrace ffsll getcwd getpagesize getrusage gettimeofday
do
as_ac_var=`echo "ac_cv_func_$ac_func" | $as_tr_sh`
echo "$as_me:$LINENO: checking for $ac_func" >&5
@@ -27331,7 +27331,8 @@
-for ac_func in mkdtemp mkstemp mktemp
+
+for ac_func in isatty mkdtemp mkstemp mktemp
do
as_ac_var=`echo "ac_cv_func_$ac_func" | $as_tr_sh`
echo "$as_me:$LINENO: checking for $ac_func" >&5
diff --git a/lib/Transforms/IPO/SimplifyLibCalls.cpp b/lib/Transforms/IPO/SimplifyLibCalls.cpp
index 24bcf4e..951516a 100644
--- a/lib/Transforms/IPO/SimplifyLibCalls.cpp
+++ b/lib/Transforms/IPO/SimplifyLibCalls.cpp
@@ -1672,6 +1672,80 @@
}
} ToAsciiOptimizer;
+#if defined(HAVE_FFSLL)
+/// This LibCallOptimization will simplify calls to the "ffs" library
+/// calls which find the first set bit in an int, long, or long long. The
+/// optimization is to compute the result at compile time if the argument is
+/// a constant.
+/// @brief Simplify the ffs library function.
+struct FFSOptimization : public LibCallOptimization
+{
+protected:
+ /// @brief Subclass Constructor
+ FFSOptimization(const char* funcName, const char* description)
+ : LibCallOptimization(funcName, description)
+ {}
+
+public:
+ /// @brief Default Constructor
+ FFSOptimization() : LibCallOptimization("ffs",
+ "Number of 'ffs' calls simplified") {}
+
+ /// @brief Destructor
+ virtual ~FFSOptimization() {}
+
+ /// @brief Make sure that the "fputs" function has the right prototype
+ virtual bool ValidateCalledFunction(const Function* f, SimplifyLibCalls& SLC)
+ {
+ // Just make sure this has 2 arguments
+ return (f->arg_size() == 1 && f->getReturnType() == Type::IntTy);
+ }
+
+ /// @brief Perform the ffs optimization.
+ virtual bool OptimizeCall(CallInst* ci, SimplifyLibCalls& SLC)
+ {
+ if (ConstantInt* CI = dyn_cast<ConstantInt>(ci->getOperand(1)))
+ {
+ // ffs(cnst) -> bit#
+ // ffsl(cnst) -> bit#
+ uint64_t val = CI->getRawValue();
+ int result = ffsll(static_cast<long long>(val));
+ ci->replaceAllUsesWith(ConstantSInt::get(Type::IntTy, result));
+ ci->eraseFromParent();
+ return true;
+ }
+ return false;
+ }
+} FFSOptimizer;
+
+/// This LibCallOptimization will simplify calls to the "ffsl" library
+/// calls. It simply uses FFSOptimization for which the transformation is
+/// identical.
+/// @brief Simplify the ffsl library function.
+struct FFSLOptimization : public FFSOptimization
+{
+public:
+ /// @brief Default Constructor
+ FFSLOptimization() : FFSOptimization("ffsl",
+ "Number of 'ffsl' calls simplified") {}
+
+} FFSLOptimizer;
+
+/// This LibCallOptimization will simplify calls to the "ffsll" library
+/// calls. It simply uses FFSOptimization for which the transformation is
+/// identical.
+/// @brief Simplify the ffsl library function.
+struct FFSLLOptimization : public FFSOptimization
+{
+public:
+ /// @brief Default Constructor
+ FFSLLOptimization() : FFSOptimization("ffsll",
+ "Number of 'ffsll' calls simplified") {}
+
+} FFSLLOptimizer;
+
+#endif
+
/// A function to compute the length of a null-terminated constant array of
/// integers. This function can't rely on the size of the constant array
/// because there could be a null terminator in the middle of the array.
@@ -1788,9 +1862,6 @@
// exp, expf, expl:
// * exp(log(x)) -> x
//
-// ffs, ffsl, ffsll:
-// * ffs(cnst) -> cnst'
-//
// isascii:
// * isascii(c) -> ((c & ~0x7f) == 0)
//