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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@71442 91177308-0d34-0410-b5e6-96231b3b80d8
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Chris Lattner 2009-05-11 17:36:33 +00:00
parent c1acc3f764
commit d919a8bc8a
1 changed files with 35 additions and 0 deletions
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35
lib/Target/README.txt
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@ -1717,3 +1717,38 @@ int int_char(char m) {if(m>7) return 0; return m;}
//===---------------------------------------------------------------------===//
InstCombine's "turn load from constant into constant" optimization should be
more aggressive in the presence of bitcasts. For example, because of unions,
this code:
union vec2d {
double e[2];
double v __attribute__((vector_size(16)));
};
typedef union vec2d vec2d;
static vec2d a={{1,2}}, b={{3,4}};
vec2d foo () {
return (vec2d){ .v = a.v + b.v * (vec2d){{5,5}}.v };
}
Compiles into:
@a = internal constant %0 { [2 x double]
[double 1.000000e+00, double 2.000000e+00] }, align 16
@b = internal constant %0 { [2 x double]
[double 3.000000e+00, double 4.000000e+00] }, align 16
...
define void @foo(%struct.vec2d* noalias nocapture sret %agg.result) nounwind {
entry:
%0 = load <2 x double>* getelementptr (%struct.vec2d*
bitcast (%0* @a to %struct.vec2d*), i32 0, i32 0), align 16
%1 = load <2 x double>* getelementptr (%struct.vec2d*
bitcast (%0* @b to %struct.vec2d*), i32 0, i32 0), align 16
Instcombine should be able to optimize away the loads (and thus the globals).
//===---------------------------------------------------------------------===//