Rename isWeakForLinker to mayBeOverridden. Use it

[oota-llvm.git] / lib / Target / PowerPC / README.txt

diff --git a/lib/Target/PowerPC/README.txt b/lib/Target/PowerPC/README.txt
index 2ae4088293af50589b557fa7a32ac7749270d339..e5d4002846ebde813221a819f09791f386d53699 100644 (file)
--- a/lib/Target/PowerPC/README.txt
+++ b/lib/Target/PowerPC/README.txt
@@ -3,7 +3,6 @@
 TODO:
 * gpr0 allocation
 * implement do-loop -> bdnz transform
-* Implement __builtin_trap (ISD::TRAP) as 'tw 31, 0, 0' aka 'trap'.
 * lmw/stmw pass a la arm load store optimizer for prolog/epilog
 
 ===-------------------------------------------------------------------------===
@@ -154,29 +153,6 @@ 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() {
@@ -737,3 +713,42 @@ GCC compiles this into:
 which is more efficient and can use mfocr.  See PR642 for some more context.
 
 //===---------------------------------------------------------------------===//
+
+void foo(float *data, float d) {
+   long i;
+   for (i = 0; i < 8000; i++)
+      data[i] = d;
+}
+void foo2(float *data, float d) {
+   long i;
+   data--;
+   for (i = 0; i < 8000; i++) {
+      data[1] = d;
+      data++;
+   }
+}
+
+These compile to:
+
+_foo:
+       li r2, 0
+LBB1_1:        ; bb
+       addi r4, r2, 4
+       stfsx f1, r3, r2
+       cmplwi cr0, r4, 32000
+       mr r2, r4
+       bne cr0, LBB1_1 ; bb
+       blr 
+_foo2:
+       li r2, 0
+LBB2_1:        ; bb
+       addi r4, r2, 4
+       stfsx f1, r3, r2
+       cmplwi cr0, r4, 32000
+       mr r2, r4
+       bne cr0, LBB2_1 ; bb
+       blr 
+
+The 'mr' could be eliminated to folding the add into the cmp better.
+
+//===---------------------------------------------------------------------===//