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authorNate Begeman <natebegeman@mac.com>2006-02-04 07:29:35 +0000
committerNate Begeman <natebegeman@mac.com>2006-02-04 07:29:35 +0000
commita6973c348bb92e672cad5b599cc4bff09c9e4b10 (patch)
tree0e3d54133603e2260d0e8394ab8e67047849f200
parent0d913eaaed3202231e8a332b12153c4b7a5f43c5 (diff)
Remove some stuff that now works
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25963 91177308-0d34-0410-b5e6-96231b3b80d8
-rw-r--r--lib/Target/PowerPC/README.txt53
1 files changed, 0 insertions, 53 deletions
diff --git a/lib/Target/PowerPC/README.txt b/lib/Target/PowerPC/README.txt
index f90073f2ca..46c36cbfe6 100644
--- a/lib/Target/PowerPC/README.txt
+++ b/lib/Target/PowerPC/README.txt
@@ -198,59 +198,6 @@ currently only commutes to avoid inserting a copy BEFORE the two addr instr.
===-------------------------------------------------------------------------===
-176.gcc contains a bunch of code like this (this occurs dozens of times):
-
-int %test(uint %mode.0.i.0) {
- %tmp.79 = cast uint %mode.0.i.0 to sbyte ; <sbyte> [#uses=1]
- %tmp.80 = cast sbyte %tmp.79 to int ; <int> [#uses=1]
- %tmp.81 = shl int %tmp.80, ubyte 16 ; <int> [#uses=1]
- %tmp.82 = and int %tmp.81, 16711680
- ret int %tmp.82
-}
-
-which we compile to:
-
-_test:
- extsb r2, r3
- rlwinm r3, r2, 16, 8, 15
- blr
-
-The extsb is obviously dead. This can be handled by a future thing like
-MaskedValueIsZero that checks to see if bits are ever demanded (in this case,
-the sign bits are never used, so we can fold the sext_inreg to nothing).
-
-I'm seeing code like this:
-
- srwi r3, r3, 16
- extsb r3, r3
- rlwimi r4, r3, 16, 8, 15
-
-in which the extsb is preventing the srwi from being nuked.
-
-===-------------------------------------------------------------------------===
-
-Another example that occurs is:
-
-uint %test(int %specbits.6.1) {
- %tmp.2540 = shr int %specbits.6.1, ubyte 11 ; <int> [#uses=1]
- %tmp.2541 = cast int %tmp.2540 to uint ; <uint> [#uses=1]
- %tmp.2542 = shl uint %tmp.2541, ubyte 13 ; <uint> [#uses=1]
- %tmp.2543 = and uint %tmp.2542, 8192 ; <uint> [#uses=1]
- ret uint %tmp.2543
-}
-
-which we codegen as:
-
-l1_test:
- srawi r2, r3, 11
- rlwinm r3, r2, 13, 18, 18
- blr
-
-the srawi can be nuked by turning the SAR into a logical SHR (the sext bits are
-dead), which I think can then be folded into the rlwinm.
-
-===-------------------------------------------------------------------------===
-
Compile offsets from allocas:
int *%test() {