adding another optimization opportunity to readme file

llvm-svn: 263775

diff --git a/llvm/lib/Target/PowerPC/README.txt b/llvm/lib/Target/PowerPC/README.txt
index 01233ae..f1d4ca7 100644 (file)
--- a/llvm/lib/Target/PowerPC/README.txt
+++ b/llvm/lib/Target/PowerPC/README.txt
@@ -589,6 +589,17 @@ entry:
        %tmp34 = zext i1 %tmp3 to i32           ; <i32> [#uses=1]
        ret i32 %tmp34
 }
+
+//===---------------------------------------------------------------------===//
+for the following code:
+
+void foo (float *__restrict__ a, int *__restrict__ b, int n) {
+      a[n] = b[n]  * 2.321;
+}
+
+we load b[n] to GPR, then move it VSX register and convert it float. We should 
+use vsx scalar integer load instructions to avoid direct moves
+
 //===----------------------------------------------------------------------===//
 ; RUN: llvm-as < %s | llc -march=ppc32 | not grep fneg