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Add an easy microoptimization I noticed.

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llvm-svn: 43164
This commit is contained in:
Chris Lattner 2007-10-19 03:29:26 +00:00
parent 9b11c8ab03
commit 57e2fa4ba0
1 changed files with 19 additions and 0 deletions
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19
lib/Target/ARM/README.txt
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@ -573,3 +573,22 @@ __Z11no_overflowjj:
bx lr
//===---------------------------------------------------------------------===//
Easy ARM microoptimization (with -mattr=+vfp2):
define i64 @i(double %X) {
%Y = bitcast double %X to i64
ret i64 %Y
}
compiles into:
_i:
fmdrr d0, r0, r1
fmrrd r0, r1, d0
bx lr
This just needs a target-specific dag combine to merge the two ARMISD nodes.
//===---------------------------------------------------------------------===//