R600/SI: Try to keep i32 mul on SALU

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

diff --git a/lib/Target/README.txt b/lib/Target/README.txt
index a9aab86abdacb830e02f8c364723e8ed94f25541..bf8d465d0aeebe9db2b1a2e5375fef188fa8853c 100644 (file)
--- a/lib/Target/README.txt
+++ b/lib/Target/README.txt
@@ -93,44 +93,6 @@ This requires reassociating to forms of expressions that are already available,
 something that reassoc doesn't think about yet.
 
 
-//===---------------------------------------------------------------------===//
-
-This function: (derived from GCC PR19988)
-double foo(double x, double y) {
-  return ((x + 0.1234 * y) * (x + -0.1234 * y));
-}
-
-compiles to:
-_foo:
-       movapd  %xmm1, %xmm2
-       mulsd   LCPI1_1(%rip), %xmm1
-       mulsd   LCPI1_0(%rip), %xmm2
-       addsd   %xmm0, %xmm1
-       addsd   %xmm0, %xmm2
-       movapd  %xmm1, %xmm0
-       mulsd   %xmm2, %xmm0
-       ret
-
-Reassociate should be able to turn it into:
-
-double foo(double x, double y) {
-  return ((x + 0.1234 * y) * (x - 0.1234 * y));
-}
-
-Which allows the multiply by constant to be CSE'd, producing:
-
-_foo:
-       mulsd   LCPI1_0(%rip), %xmm1
-       movapd  %xmm1, %xmm2
-       addsd   %xmm0, %xmm2
-       subsd   %xmm1, %xmm0
-       mulsd   %xmm2, %xmm0
-       ret
-
-This doesn't need -ffast-math support at all.  This is particularly bad because
-the llvm-gcc frontend is canonicalizing the later into the former, but clang
-doesn't have this problem.
-
 //===---------------------------------------------------------------------===//
 
 These two functions should generate the same code on big-endian systems:
@@ -1163,7 +1125,7 @@ There are many load PRE testcases in testsuite/gcc.dg/tree-ssa/loadpre* in the
 GCC testsuite, ones we don't get yet are (checked through loadpre25):
 
 [CRIT EDGE BREAKING]
-loadpre3.c predcom-4.c
+predcom-4.c
 
 [PRE OF READONLY CALL]
 loadpre5.c