Rong Xu 40080ca01c Conditionally eliminate library calls where the result value is not used ... Summary: This pass shrink-wraps a condition to some library calls where the call result is not used. For example: sqrt(val); is transformed to if (val < 0) sqrt(val); Even if the result of library call is not being used, the compiler cannot safely delete the call because the function can set errno on error conditions. Note in many functions, the error condition solely depends on the incoming parameter. In this optimization, we can generate the condition can lead to the errno to shrink-wrap the call. Since the chances of hitting the error condition is low, the runtime call is effectively eliminated. These partially dead calls are usually results of C++ abstraction penalty exposed by inlining. This optimization hits 108 times in 19 C/C++ programs in SPEC2006. Reviewers: hfinkel, mehdi_amini, davidxl Subscribers: modocache, mgorny, mehdi_amini, xur, llvm-commits, beanz Differential Revision: https://reviews.llvm.org/D24414 llvm-svn: 284542		2016-10-18 21:36:27 +00:00
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CMakeLists.txt
LLVMBuild.txt	Add missing dependency to LLVMPasses	2016-06-24 21:05:41 +00:00
PassBuilder.cpp	Conditionally eliminate library calls where the result value is not used	2016-10-18 21:36:27 +00:00
PassRegistry.def	Conditionally eliminate library calls where the result value is not used	2016-10-18 21:36:27 +00:00