diff --git a/lib/Target/PowerPC/README.txt b/lib/Target/PowerPC/README.txt index 2897655d2d0..58805562a87 100644 --- a/lib/Target/PowerPC/README.txt +++ b/lib/Target/PowerPC/README.txt @@ -241,3 +241,35 @@ _test: --> important for C++. +===-------------------------------------------------------------------------=== + +int test3(int a, int b) { return (a < 0) ? a : 0; } + +should be branch free code. LLVM is turning it into < 1 because of the RHS. + +===-------------------------------------------------------------------------=== + +For this testcase: +int f1(int a, int b) { return (a&0xF)|(b&0xF0); } + +We currently emit: +_f1: + rlwinm r2, r4, 0, 24, 27 + rlwimi r2, r3, 0, 28, 31 + or r3, r2, r2 + blr + +We could emit: +_f1: + rlwinm r4, r4, 0, 24, 27 + rlwimi r3, r4, 0, 0, 27 + blr + +===-------------------------------------------------------------------------=== + +No loads or stores of the constants should be needed: + +struct foo { double X, Y; }; +void xxx(struct foo F); +void bar() { struct foo R = { 1.0, 2.0 }; xxx(R); } +