X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FTarget%2FREADME.txt;h=bf8d465d0aeebe9db2b1a2e5375fef188fa8853c;hb=12af22e8cc217827cf4f118b0f5e4ebbda9925ae;hp=8929ac4f2a610aad46fb37dc83bbc90f6c5f2996;hpb=f2fd23b0620b3785a85fbde8893ffd777ed8b2b2;p=oota-llvm.git

diff --git a/lib/Target/README.txt b/lib/Target/README.txt
index 8929ac4f2a6..bf8d465d0ae 100644
--- a/lib/Target/README.txt
+++ b/lib/Target/README.txt
@@ -2,22 +2,6 @@ Target Independent Opportunities:
 
 //===---------------------------------------------------------------------===//
 
-With the recent changes to make the implicit def/use set explicit in
-machineinstrs, we should change the target descriptions for 'call' instructions
-so that the .td files don't list all the call-clobbered registers as implicit
-defs.  Instead, these should be added by the code generator (e.g. on the dag).
-
-This has a number of uses:
-
-1. PPC32/64 and X86 32/64 can avoid having multiple copies of call instructions
-   for their different impdef sets.
-2. Targets with multiple calling convs (e.g. x86) which have different clobber
-   sets don't need copies of call instructions.
-3. 'Interprocedural register allocation' can be done to reduce the clobber sets
-   of calls.
-
-//===---------------------------------------------------------------------===//
-
 We should recognized various "overflow detection" idioms and translate them into
 llvm.uadd.with.overflow and similar intrinsics.  Here is a multiply idiom:
 
@@ -109,44 +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:
@@ -168,7 +114,7 @@ stuff too.
 
 //===---------------------------------------------------------------------===//
 
-For vector types, TargetData.cpp::getTypeInfo() returns alignment that is equal
+For vector types, DataLayout.cpp::getTypeInfo() returns alignment that is equal
 to the type size. It works but can be overly conservative as the alignment of
 specific vector types are target dependent.
 
@@ -278,22 +224,7 @@ unsigned countbits_slow(unsigned v) {
     c += v & 1;
   return c;
 }
-unsigned countbits_fast(unsigned v){
-  unsigned c;
-  for (c = 0; v; c++)
-    v &= v - 1; // clear the least significant bit set
-  return c;
-}
 
-BITBOARD = unsigned long long
-int PopCnt(register BITBOARD a) {
-  register int c=0;
-  while(a) {
-    c++;
-    a &= a - 1;
-  }
-  return c;
-}
 unsigned int popcount(unsigned int input) {
   unsigned int count = 0;
   for (unsigned int i =  0; i < 4 * 8; i++)
@@ -973,6 +904,19 @@ optimized with "clang -emit-llvm-bc | opt -std-compile-opts".
 
 //===---------------------------------------------------------------------===//
 
+int f(int i, int j) { return i < j + 1; }
+int g(int i, int j) { return j > i - 1; }
+Should combine to "i <= j" (the add/sub has nsw).  Currently not
+optimized with "clang -emit-llvm-bc | opt -std-compile-opts".
+
+//===---------------------------------------------------------------------===//
+
+unsigned f(unsigned x) { return ((x & 7) + 1) & 15; }
+The & 15 part should be optimized away, it doesn't change the result. Currently
+not optimized with "clang -emit-llvm-bc | opt -std-compile-opts".
+
+//===---------------------------------------------------------------------===//
+
 This was noticed in the entryblock for grokdeclarator in 403.gcc:
 
         %tmp = icmp eq i32 %decl_context, 4          
@@ -1181,7 +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
@@ -2370,8 +2314,3 @@ unsigned foo(unsigned x, unsigned y) { return x > y && x != 0; }
 should fold to x > y.
 
 //===---------------------------------------------------------------------===//
-
-int f(double x) { return __builtin_fabs(x) < 0.0; }
-should fold to false.
-
-//===---------------------------------------------------------------------===//