Remove outdated README entry.

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

diff --git a/lib/Target/README.txt b/lib/Target/README.txt
index ea9bc8d84c8c0fc67592b5087e06b39ce64b27b6..5aa29782afde9ec7d9378f6d98539b4a5553053d 100644 (file)
--- a/lib/Target/README.txt
+++ b/lib/Target/README.txt
@@ -289,14 +289,6 @@ unsigned int popcount(unsigned int input) {
 
 This sort of thing should be added to the loop idiom pass.
 
-This loop isn't converted to a memset:
-
-void f(char *dest, int n) {
-  for (int i = 0; i < n; ++i) {
-    dest[n] = 0;
-  }
-}
-
 //===---------------------------------------------------------------------===//
 
 These should turn into single 16-bit (unaligned?) loads on little/big endian
@@ -741,18 +733,6 @@ codegen badness or something else (haven't investigated).
 
 //===---------------------------------------------------------------------===//
 
-We miss some instcombines for stuff like this:
-void bar (void);
-void foo (unsigned int a) {
-  /* This one is equivalent to a >= (3 << 2).  */
-  if ((a >> 2) >= 3)
-    bar ();
-}
-
-A few other related ones are in GCC PR14753.
-
-//===---------------------------------------------------------------------===//
-
 Divisibility by constant can be simplified (according to GCC PR12849) from
 being a mulhi to being a mul lo (cheaper).  Testcase:
 
@@ -1270,26 +1250,6 @@ SingleSource/Benchmarks/Misc/dt.c
 
 //===---------------------------------------------------------------------===//
 
-A/B get pinned to the stack because we turn an if/then into a select instead
-of PRE'ing the load/store.  This may be fixable in instcombine:
-http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37892
-
-struct X { int i; };
-int foo (int x) {
-  struct X a;
-  struct X b;
-  struct X *p;
-  a.i = 1;
-  b.i = 2;
-  if (x)
-    p = &a;
-  else
-    p = &b;
-  return p->i;
-}
-
-//===---------------------------------------------------------------------===//
-
 Interesting missed case because of control flow flattening (should be 2 loads):
 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26629
 With: llvm-gcc t2.c -S -o - -O0 -emit-llvm | llvm-as | 
@@ -1811,13 +1771,12 @@ entry:
 }
 
 Generated code:
-       addq    %rcx, %rdx
-       movl    $0, %eax
-       adcq    $0, %rax
-       addq    %r8, %rax
-       movq    %rax, (%rdi)
-       movq    %rdx, (%rsi)
-       ret
+        addq   %rcx, %rdx
+        sbbq   %rax, %rax
+        subq   %rax, %r8
+        movq   %r8, (%rdi)
+        movq   %rdx, (%rsi)
+        ret
 
 Expected code:
        addq    %rcx, %rdx
@@ -1826,12 +1785,6 @@ Expected code:
        movq    %rdx, (%rsi)
        ret
 
-The generated SelectionDAG has an ADD of an ADDE, where both operands of the
-ADDE are zero. Replacing one of the operands of the ADDE with the other operand
-of the ADD, and replacing the ADD with the ADDE, should give the desired result.
-
-(That said, we are doing a lot better than gcc on this testcase. :) )
-
 //===---------------------------------------------------------------------===//
 
 Switch lowering generates less than ideal code for the following switch:
@@ -1875,43 +1828,6 @@ something like the following, which eliminates a branch:
        ret
 .LBB0_2:
        jmp     foo  # TAILCALL
-//===---------------------------------------------------------------------===//
-Given a branch where the two target blocks are identical ("ret i32 %b" in
-both), simplifycfg will simplify them away. But not so for a switch statement:
-
-define i32 @f(i32 %a, i32 %b) nounwind readnone {
-entry:
-        switch i32 %a, label %bb3 [
-                i32 4, label %bb
-                i32 6, label %bb
-        ]
-
-bb:             ; preds = %entry, %entry
-        ret i32 %b
-
-bb3:            ; preds = %entry
-        ret i32 %b
-}
-//===---------------------------------------------------------------------===//
-
-clang -O3 fails to devirtualize this virtual inheritance case: (GCC PR45875)
-Looks related to PR3100
-
-struct c1 {};
-struct c10 : c1{
-  virtual void foo ();
-};
-struct c11 : c10, c1{
-  virtual void f6 ();
-};
-struct c28 : virtual c11{
-  void f6 ();
-};
-void check_c28 () {
-  c28 obj;
-  c11 *ptr = &obj;
-  ptr->f6 ();
-}
 
 //===---------------------------------------------------------------------===//
 
@@ -2302,24 +2218,3 @@ llc time when it gets inlined, because we can use smaller transfers.  This also
 avoids partial register stalls in some important cases.
 
 //===---------------------------------------------------------------------===//
-
-We miss an optzn when lowering divide by some constants.  For example:
-  int test(int x) { return x/10; }
-
-We produce:
-
-_test:                                  ## @test
-## BB#0:                                ## %entry
-       movslq  %edi, %rax
-       imulq   $1717986919, %rax, %rax ## imm = 0x66666667
-       movq    %rax, %rcx
-       shrq    $63, %rcx
-**     shrq    $32, %rax
-**      sarl   $2, %eax
-       addl    %ecx, %eax
-       ret
-
-The two starred instructions could be replaced with a "sarl $34, %rax".  This
-occurs in 186.crafty very frequently.
-
-//===---------------------------------------------------------------------===//