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some stuff is done, we still have constantexpr simplification to do.

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@84943 91177308-0d34-0410-b5e6-96231b3b80d8
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Chris Lattner 2009-10-23 07:00:55 +00:00
parent 17f0cd3cc1
commit 9ff9b34dd1
1 changed files with 15 additions and 31 deletions
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46
lib/Target/README.txt
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@ -1594,23 +1594,8 @@ int int_char(char m) {if(m>7) return 0; return m;}
//===---------------------------------------------------------------------===//
Instcombine should replace the load with a constant in:
static const char x[4] = {'a', 'b', 'c', 'd'};
unsigned int y(void) {
return *(unsigned int *)x;
}
It currently only does this transformation when the size of the constant
is the same as the size of the integer (so, try x[5]) and the last byte
is a null (making it a C string). There's no need for these restrictions.
//===---------------------------------------------------------------------===//
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:
libanalysis is not aggressively folding vector bitcasts. For example, the
constant expressions generated when compiling this code:
union vec2d {
double e[2];
@ -1624,24 +1609,23 @@ vec2d foo () {
return (vec2d){ .v = a.v + b.v * (vec2d){{5,5}}.v };
}
Compiles into:
in X86-32 end up being:
@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 {
define void @foo(%union.vec2d* noalias nocapture sret %agg.result) nounwind ssp {
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
%agg.result.0 = getelementptr %union.vec2d* %agg.result, i32 0, i32 0 ; <<2 x double>*> [#uses=1]
store <2 x double> fadd (<2 x double> bitcast (<1 x i128> <i128 85070591730234615870450834276742070272> to <2 x double>), <2 x double> fmul (<2 x double> bitcast (<1 x i128> <i128 85153668479971173112514077617450647552> to <2 x double>), <2 x double> <double 5.000000e+00, double 5.000000e+00>)), <2 x double>* %agg.result.0, align 16
ret void
}
and in X86-64 mode:
Instcombine should be able to optimize away the loads (and thus the globals).
See also PR4973
define %0 @foo() nounwind readnone ssp {
entry:
%mrv5 = insertvalue %0 undef, double extractelement (<2 x double> fadd (<2 x double> bitcast (<1 x i128> <i128 85070591730234615870450834276742070272> to <2 x double>), <2 x double> fmul (<2 x double> bitcast (<1 x i128> <i128 85153668479971173112514077617450647552> to <2 x double>), <2 x double> bitcast (<1 x i128> <i128 85174437667405312423031577302488055808> to <2 x double>))), i32 0), 0 ; <%0> [#uses=1]
%mrv6 = insertvalue %0 %mrv5, double extractelement (<2 x double> fadd (<2 x double> bitcast (<1 x i128> <i128 85070591730234615870450834276742070272> to <2 x double>), <2 x double> fmul (<2 x double> bitcast (<1 x i128> <i128 85153668479971173112514077617450647552> to <2 x double>), <2 x double> bitcast (<1 x i128> <i128 85174437667405312423031577302488055808> to <2 x double>))), i32 1), 1 ; <%0> [#uses=1]
ret %0 %mrv6
}
//===---------------------------------------------------------------------===//