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eb1c51f8b3
Juergen Ributzka
eb1c51f8b3
[FastISel] Let the target decide first if it wants to materialize a constant.
This changes the order in which FastISel tries to materialize a constant. Originally it would try to use a simple target-independent approach, which can lead to the generation of inefficient code. On X86 this would result in the use of movabsq to materialize any 64bit integer constant - even for simple and small values such as 0 and 1. Also some very funny floating-point materialization could be observed too. On AArch64 it would materialize the constant 0 in a register even the architecture has an actual "zero" register. On ARM it would generate unnecessary mov instructions or not use mvn. This change simply changes the order and always asks the target first if it likes to materialize the constant. This doesn't fix all the issues mentioned above, but it enables the targets to implement such optimizations. Related to <rdar://problem/17420988>. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215588 91177308-0d34-0410-b5e6-96231b3b80d8
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