Changes in directory llvm/lib/Target/PowerPC:
README.txt updated: 1.37 -> 1.38
---
Log message:
add a case Nate sent me
---
Diffs of the changes: (+23 -0)
README.txt | 23 +++++++++++++++++++++++
1 files changed, 23 insertions(+)
Index: llvm/lib/Target/PowerPC/README.txt
diff -u llvm/lib/Target/PowerPC/README.txt:1.37
llvm/lib/Target/PowerPC/README.txt:1.38
--- llvm/lib/Target/PowerPC/README.txt:1.37 Sun Oct 30 01:42:12 2005
+++ llvm/lib/Target/PowerPC/README.txt Sat Nov 5 02:57:56 2005
@@ -217,3 +217,26 @@
stw r2, 0(r3)
blr
+===-------------------------------------------------------------------------===
+
+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.
+
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