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Evan implemented this.

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llvm-svn: 47827
This commit is contained in:
Chris Lattner 2008-03-02 17:56:29 +00:00
parent 7f3c8ea9bf
commit 4c67781884
2 changed files with 8 additions and 23 deletions
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23
lib/Target/PowerPC/README.txt
View File

@ -154,29 +154,6 @@ more than one use. Itanium will want this too.
===-------------------------------------------------------------------------===
Compile this:
int %f1(int %a, int %b) {
%tmp.1 = and int %a, 15 ; <int> [#uses=1]
%tmp.3 = and int %b, 240 ; <int> [#uses=1]
%tmp.4 = or int %tmp.3, %tmp.1 ; <int> [#uses=1]
ret int %tmp.4
}
without a copy. We make this currently:
_f1:
rlwinm r2, r4, 0, 24, 27
rlwimi r2, r3, 0, 28, 31
or r3, r2, r2
blr
The two-addr pass or RA needs to learn when it is profitable to commute an
instruction to avoid a copy AFTER the 2-addr instruction. The 2-addr pass
currently only commutes to avoid inserting a copy BEFORE the two addr instr.
===-------------------------------------------------------------------------===
Compile offsets from allocas:
int *%test() {

8
test/CodeGen/PowerPC/rlwimi-commute.ll
View File

@ -24,3 +24,11 @@ define void @test2(i32* %A, i32* %B, i32* %D, i32* %E) {
store i32 %B.upgrd.4, i32* %E
ret void
}
define i32 @test3(i32 %a, i32 %b) {
%tmp.1 = and i32 %a, 15 ; <i32> [#uses=1]
%tmp.3 = and i32 %b, 240 ; <i32> [#uses=1]
%tmp.4 = or i32 %tmp.3, %tmp.1 ; <i32> [#uses=1]
ret i32 %tmp.4
}