Reformat comment lines.

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

diff --git a/lib/Target/README.txt b/lib/Target/README.txt
index 7619b7fe3849245b8674f291a869c4ae91fde1cc..7e9888cc13e80b48466cb5cca8997819eb07cb92 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.
 
 
 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:
 //===---------------------------------------------------------------------===//
 
 These two functions should generate the same code on big-endian systems:


@@ -144,7 +106,7 @@ for 1,2,4,8 bytes.
 //===---------------------------------------------------------------------===//
 
 It would be nice to revert this patch:
 //===---------------------------------------------------------------------===//
 
 It would be nice to revert this patch:

-http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20060213/031986.html
+http://lists.llvm.org/pipermail/llvm-commits/Week-of-Mon-20060213/031986.html

 
 And teach the dag combiner enough to simplify the code expanded before 
 legalize.  It seems plausible that this knowledge would let it simplify other
 
 And teach the dag combiner enough to simplify the code expanded before 
 legalize.  It seems plausible that this knowledge would let it simplify other


@@ -152,7 +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.
 
 to the type size. It works but can be overly conservative as the alignment of
 specific vector types are target dependent.
 


@@ -262,22 +224,7 @@ unsigned countbits_slow(unsigned v) {
     c += v & 1;
   return c;
 }
     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++)
 unsigned int popcount(unsigned int input) {
   unsigned int count = 0;
   for (unsigned int i =  0; i < 4 * 8; i++)


@@ -786,7 +733,7 @@ f (unsigned long a, unsigned long b, unsigned long c)
   return ((a & (c - 1)) != 0) | ((b & (c - 1)) != 0);
 }
 Both should combine to ((a|b) & (c-1)) != 0.  Currently not optimized with
   return ((a & (c - 1)) != 0) | ((b & (c - 1)) != 0);
 }
 Both should combine to ((a|b) & (c-1)) != 0.  Currently not optimized with

-"clang -emit-llvm-bc | opt -std-compile-opts".
+"clang -emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 
 //===---------------------------------------------------------------------===//
 


@@ -799,7 +746,7 @@ void clear_pmd_range(unsigned long start, unsigned long end)
 }
 The expression should optimize to something like
 "!((start|end)&~PMD_MASK). Currently not optimized with "clang
 }
 The expression should optimize to something like
 "!((start|end)&~PMD_MASK). Currently not optimized with "clang

--emit-llvm-bc | opt -std-compile-opts".
+-emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 
 //===---------------------------------------------------------------------===//
 


@@ -818,7 +765,7 @@ int f(int x, int y)
  return (abs(x)) >= 0;
 }
 This should optimize to x == INT_MIN. (With -fwrapv.)  Currently not
  return (abs(x)) >= 0;
 }
 This should optimize to x == INT_MIN. (With -fwrapv.)  Currently not

-optimized with "clang -emit-llvm-bc | opt -std-compile-opts".
+optimized with "clang -emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 
 //===---------------------------------------------------------------------===//
 


@@ -856,117 +803,117 @@ rshift_gt (unsigned int a)
 
 All should simplify to a single comparison.  All of these are
 currently not optimized with "clang -emit-llvm-bc | opt
 
 All should simplify to a single comparison.  All of these are
 currently not optimized with "clang -emit-llvm-bc | opt

--std-compile-opts".
+-O3".

 
 //===---------------------------------------------------------------------===//
 
 From GCC Bug 32605:
 int c(int* x) {return (char*)x+2 == (char*)x;}
 Should combine to 0.  Currently not optimized with "clang
 
 //===---------------------------------------------------------------------===//
 
 From GCC Bug 32605:
 int c(int* x) {return (char*)x+2 == (char*)x;}
 Should combine to 0.  Currently not optimized with "clang

--emit-llvm-bc | opt -std-compile-opts" (although llc can optimize it).
+-emit-llvm-bc | opt -O3" (although llc can optimize it).

 
 //===---------------------------------------------------------------------===//
 
 int a(unsigned b) {return ((b << 31) | (b << 30)) >> 31;}
 Should be combined to  "((b >> 1) | b) & 1".  Currently not optimized
 
 //===---------------------------------------------------------------------===//
 
 int a(unsigned b) {return ((b << 31) | (b << 30)) >> 31;}
 Should be combined to  "((b >> 1) | b) & 1".  Currently not optimized

-with "clang -emit-llvm-bc | opt -std-compile-opts".
+with "clang -emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 unsigned a(unsigned x, unsigned y) { return x | (y & 1) | (y & 2);}
 Should combine to "x | (y & 3)".  Currently not optimized with "clang
 
 //===---------------------------------------------------------------------===//
 
 unsigned a(unsigned x, unsigned y) { return x | (y & 1) | (y & 2);}
 Should combine to "x | (y & 3)".  Currently not optimized with "clang

--emit-llvm-bc | opt -std-compile-opts".
+-emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 int a(int a, int b, int c) {return (~a & c) | ((c|a) & b);}
 Should fold to "(~a & c) | (a & b)".  Currently not optimized with
 
 //===---------------------------------------------------------------------===//
 
 int a(int a, int b, int c) {return (~a & c) | ((c|a) & b);}
 Should fold to "(~a & c) | (a & b)".  Currently not optimized with

-"clang -emit-llvm-bc | opt -std-compile-opts".
+"clang -emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 int a(int a,int b) {return (~(a|b))|a;}
 Should fold to "a|~b".  Currently not optimized with "clang
 
 //===---------------------------------------------------------------------===//
 
 int a(int a,int b) {return (~(a|b))|a;}
 Should fold to "a|~b".  Currently not optimized with "clang

--emit-llvm-bc | opt -std-compile-opts".
+-emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 int a(int a, int b) {return (a&&b) || (a&&!b);}
 Should fold to "a".  Currently not optimized with "clang -emit-llvm-bc
 
 //===---------------------------------------------------------------------===//
 
 int a(int a, int b) {return (a&&b) || (a&&!b);}
 Should fold to "a".  Currently not optimized with "clang -emit-llvm-bc

-| opt -std-compile-opts".
+| opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 int a(int a, int b, int c) {return (a&&b) || (!a&&c);}
 Should fold to "a ? b : c", or at least something sane.  Currently not
 
 //===---------------------------------------------------------------------===//
 
 int a(int a, int b, int c) {return (a&&b) || (!a&&c);}
 Should fold to "a ? b : c", or at least something sane.  Currently not

-optimized with "clang -emit-llvm-bc | opt -std-compile-opts".
+optimized with "clang -emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 int a(int a, int b, int c) {return (a&&b) || (a&&c) || (a&&b&&c);}
 Should fold to a && (b || c).  Currently not optimized with "clang
 
 //===---------------------------------------------------------------------===//
 
 int a(int a, int b, int c) {return (a&&b) || (a&&c) || (a&&b&&c);}
 Should fold to a && (b || c).  Currently not optimized with "clang

--emit-llvm-bc | opt -std-compile-opts".
+-emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 int a(int x) {return x | ((x & 8) ^ 8);}
 Should combine to x | 8.  Currently not optimized with "clang
 
 //===---------------------------------------------------------------------===//
 
 int a(int x) {return x | ((x & 8) ^ 8);}
 Should combine to x | 8.  Currently not optimized with "clang

--emit-llvm-bc | opt -std-compile-opts".
+-emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 int a(int x) {return x ^ ((x & 8) ^ 8);}
 Should also combine to x | 8.  Currently not optimized with "clang
 
 //===---------------------------------------------------------------------===//
 
 int a(int x) {return x ^ ((x & 8) ^ 8);}
 Should also combine to x | 8.  Currently not optimized with "clang

--emit-llvm-bc | opt -std-compile-opts".
+-emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 int a(int x) {return ((x | -9) ^ 8) & x;}
 Should combine to x & -9.  Currently not optimized with "clang
 
 //===---------------------------------------------------------------------===//
 
 int a(int x) {return ((x | -9) ^ 8) & x;}
 Should combine to x & -9.  Currently not optimized with "clang

--emit-llvm-bc | opt -std-compile-opts".
+-emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 unsigned a(unsigned a) {return a * 0x11111111 >> 28 & 1;}
 Should combine to "a * 0x88888888 >> 31".  Currently not optimized
 
 //===---------------------------------------------------------------------===//
 
 unsigned a(unsigned a) {return a * 0x11111111 >> 28 & 1;}
 Should combine to "a * 0x88888888 >> 31".  Currently not optimized

-with "clang -emit-llvm-bc | opt -std-compile-opts".
+with "clang -emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 unsigned a(char* x) {if ((*x & 32) == 0) return b();}
 There's an unnecessary zext in the generated code with "clang
 
 //===---------------------------------------------------------------------===//
 
 unsigned a(char* x) {if ((*x & 32) == 0) return b();}
 There's an unnecessary zext in the generated code with "clang

--emit-llvm-bc | opt -std-compile-opts".
+-emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 unsigned a(unsigned long long x) {return 40 * (x >> 1);}
 Should combine to "20 * (((unsigned)x) & -2)".  Currently not
 
 //===---------------------------------------------------------------------===//
 
 unsigned a(unsigned long long x) {return 40 * (x >> 1);}
 Should combine to "20 * (((unsigned)x) & -2)".  Currently not

-optimized with "clang -emit-llvm-bc | opt -std-compile-opts".
+optimized with "clang -emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 int g(int x) { return (x - 10) < 0; }
 Should combine to "x <= 9" (the sub has nsw).  Currently not
 
 //===---------------------------------------------------------------------===//
 
 int g(int x) { return (x - 10) < 0; }
 Should combine to "x <= 9" (the sub has nsw).  Currently not

-optimized with "clang -emit-llvm-bc | opt -std-compile-opts".
+optimized with "clang -emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 int g(int x) { return (x + 10) < 0; }
 Should combine to "x < -10" (the add has nsw).  Currently not
 
 //===---------------------------------------------------------------------===//
 
 int g(int x) { return (x + 10) < 0; }
 Should combine to "x < -10" (the add has nsw).  Currently not

-optimized with "clang -emit-llvm-bc | opt -std-compile-opts".
+optimized with "clang -emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 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
 
 //===---------------------------------------------------------------------===//
 
 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".
+optimized with "clang -emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 unsigned f(unsigned x) { return ((x & 7) + 1) & 15; }
 The & 15 part should be optimized away, it doesn't change the result. Currently
 
 //===---------------------------------------------------------------------===//
 
 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".
+not optimized with "clang -emit-llvm-bc | opt -O3".

 
 //===---------------------------------------------------------------------===//
 
 
 //===---------------------------------------------------------------------===//
 


@@ -1178,7 +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]
 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
 
 [PRE OF READONLY CALL]
 loadpre5.c


@@ -1321,7 +1268,8 @@ int foo (void) {
 ..
   else if (strchr ("<>", *intel_parser.op_string)
 
 ..
   else if (strchr ("<>", *intel_parser.op_string)
 

-Those should be turned into a switch.
+Those should be turned into a switch.  SimplifyLibCalls only gets the second
+case.

 
 //===---------------------------------------------------------------------===//
 
 
 //===---------------------------------------------------------------------===//
 


@@ -1896,44 +1844,6 @@ we remove checking in code like
 
 //===---------------------------------------------------------------------===//
 
 
 //===---------------------------------------------------------------------===//
 

-This code (from Benchmarks/Dhrystone/dry.c):
-
-define i32 @Func1(i32, i32) nounwind readnone optsize ssp {
-entry:
-  %sext = shl i32 %0, 24
-  %conv = ashr i32 %sext, 24
-  %sext6 = shl i32 %1, 24
-  %conv4 = ashr i32 %sext6, 24
-  %cmp = icmp eq i32 %conv, %conv4
-  %. = select i1 %cmp, i32 10000, i32 0
-  ret i32 %.
-}
-
-Should be simplified into something like:
-
-define i32 @Func1(i32, i32) nounwind readnone optsize ssp {
-entry:
-  %sext = shl i32 %0, 24
-  %conv = and i32 %sext, 0xFF000000
-  %sext6 = shl i32 %1, 24
-  %conv4 = and i32 %sext6, 0xFF000000
-  %cmp = icmp eq i32 %conv, %conv4
-  %. = select i1 %cmp, i32 10000, i32 0
-  ret i32 %.
-}
-
-and then to:
-
-define i32 @Func1(i32, i32) nounwind readnone optsize ssp {
-entry:
-  %conv = and i32 %0, 0xFF
-  %conv4 = and i32 %1, 0xFF
-  %cmp = icmp eq i32 %conv, %conv4
-  %. = select i1 %cmp, i32 10000, i32 0
-  ret i32 %.
-}
-//===---------------------------------------------------------------------===//
-

 clang -O3 currently compiles this code
 
 int g(unsigned int a) {
 clang -O3 currently compiles this code
 
 int g(unsigned int a) {


@@ -2367,9 +2277,3 @@ unsigned foo(unsigned x, unsigned y) { return x > y && x != 0; }
 should fold to x > y.
 
 //===---------------------------------------------------------------------===//
 should fold to x > y.
 
 //===---------------------------------------------------------------------===//

-
-int f(double x) { return __builtin_fabs(x) < 0.0; }
-should fold to false.
-
-//===---------------------------------------------------------------------===//
-