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6 Commits

Author SHA1 Message Date
Evan Cheng d983eba7dc Re-apply r124518 with fix. Watch out for invalidated iterator. 
llvm-svn: 124526
 2011-01-29 04:46:23 +00:00
Evan Cheng 65b8ccf6ac Revert r124518. It broke Linux self-host. 
llvm-svn: 124522
 2011-01-29 02:43:04 +00:00
Evan Cheng d4eff31476 Re-commit r124462 with fixes. Tail recursion elim will now dup ret into unconditional predecessor to enable TCE on demand. 
llvm-svn: 124518
 2011-01-29 01:29:26 +00:00
Evan Cheng aaa9606b2f Revert r124462. There are a few big regressions that I need to fix first. 
llvm-svn: 124478
 2011-01-28 07:12:38 +00:00
Evan Cheng 417fca86c4 - Stop simplifycfg from duplicating "ret" instructions into unconditional 
branches. PR8575, rdar://5134905, rdar://8911460.
- Allow codegen tail duplication to dup small return blocks after register
  allocation is done.

llvm-svn: 124462
 2011-01-28 02:19:21 +00:00
Jakob Stoklund Olesen 916f48a054 Teach SimplifyCFG about magic pointer constants. 
Weird code sometimes uses pointer constants other than null. This patch
teaches SimplifyCFG to build switch instructions in those cases.

Code like this:

void f(const char *x) {
  if (!x)
    puts("null");
  else if ((uintptr_t)x == 1)
    puts("one");
  else if (x == (char*)2 || x == (char*)3)
    puts("two");
  else if ((intptr_t)x == 4)
    puts("four");
  else
    puts(x);
}

Now becomes a switch:

define void @f(i8* %x) nounwind ssp {
entry:
  %magicptr23 = ptrtoint i8* %x to i64            ; <i64> [#uses=1]
  switch i64 %magicptr23, label %if.else16 [
    i64 0, label %if.then
    i64 1, label %if.then2
    i64 2, label %if.then9
    i64 3, label %if.then9
    i64 4, label %if.then14
  ]

Note that LLVM's own DenseMap uses magic pointers.

llvm-svn: 95439
 2010-02-05 22:03:18 +00:00