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e6cfdc8471
This patch adds support for a new builtin instruction called __builtin_ia32_rdpmc. Builtin '__builtin_ia32_rdpmc' is defined as a 'GCC builtin'; on X86, it can be used to read performance monitoring counters. It takes as input the index of the performance counter to read, and returns the value of the specified performance counter as a 64-bit number. Calls to this new builtin will map to instruction RDPMC. The index in input to the builtin call is moved to register %ECX. The result of the builtin call is the value of the specified performance counter (RDPMC would return that quantity in registers RDX:RAX). This patch: - Adds builtin int_x86_rdpmc as a GCCBuiltin; - Adds a new x86 DAG node called 'RDPMC_DAG'; - Teaches how to lower this new builtin; - Adds an ISel pattern to select instruction RDPMC; - Fixes the definition of instruction RDPMC adding %RAX and %RDX as implicit definitions, and adding %ECX as implicit use; - Adds a LLVM test to verify that the new builtin is correctly selected. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212049 91177308-0d34-0410-b5e6-96231b3b80d8