From 6a250ecc99c76dcb07e6431c5cb99e495895ad82 Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Fri, 13 Oct 2006 20:20:58 +0000 Subject: [PATCH] add note git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30937 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/PowerPC/README.txt | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/lib/Target/PowerPC/README.txt b/lib/Target/PowerPC/README.txt index 82af6677fa6..11ad35a56cb 100644 --- a/lib/Target/PowerPC/README.txt +++ b/lib/Target/PowerPC/README.txt @@ -11,6 +11,25 @@ still a codesize win. ===-------------------------------------------------------------------------=== +Compile: + +void foo(int *P) { + if (P) *P = 0; +} + +into: + +_foo: + cmpwi cr0,r3,0 + beqlr cr0 + li r0,0 + stw r0,0(r3) + blr + +This is effectively a simple form of predication. + +===-------------------------------------------------------------------------=== + Teach the .td file to pattern match PPC::BR_COND to appropriate bc variant, so we don't have to always run the branch selector for small functions.