[AMDGPU] Ported and adopted AMDLibCalls pass

The pass does simplifications of well known AMD library calls.
If given -amdgpu-prelink option it works in a pre-link mode which
allows to reference new library functions which will be linked in
later.

In addition it also used to process traditional AMD option
-fuse-native which allows to replace some of the functions with
their fast native implementations from the library.

The necessary glue to pass the prelink option and translate
-fuse-native is to be added to the driver.

Differential Revision: https://reviews.llvm.org/D36436

llvm-svn: 310731

llvm/lib/Target/AMDGPU/AMDGPU.h

@@ -52,6 +52,8 @@ FunctionPass *createSIDebuggerInsertNopsPass();
 FunctionPass *createSIInsertWaitsPass();
 FunctionPass *createSIInsertWaitcntsPass();
 FunctionPass *createSIFixWWMLivenessPass();
+FunctionPass *createAMDGPUSimplifyLibCallsPass();
+FunctionPass *createAMDGPUUseNativeCallsPass();
 FunctionPass *createAMDGPUCodeGenPreparePass();
 FunctionPass *createAMDGPUMachineCFGStructurizerPass();
 FunctionPass *createAMDGPURewriteOutArgumentsPass();
@@ -125,6 +127,12 @@ extern char &SIOptimizeExecMaskingID;
 void initializeSIFixWWMLivenessPass(PassRegistry &);
 extern char &SIFixWWMLivenessID;
 
+void initializeAMDGPUSimplifyLibCallsPass(PassRegistry &);
+extern char &AMDGPUSimplifyLibCallsID;
+
+void initializeAMDGPUUseNativeCallsPass(PassRegistry &);
+extern char &AMDGPUUseNativeCallsID;
+
 // Passes common to R600 and SI
 FunctionPass *createAMDGPUPromoteAlloca();
 void initializeAMDGPUPromoteAllocaPass(PassRegistry&);