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enhance the "change or icmp's into switch" xform to handle one value in an

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'or sequence' that it doesn't understand.  This allows us to optimize
something insane like this:

int crud (unsigned char c, unsigned x)
 {
   if(((((((((( (int) c <= 32 ||
                    (int) c == 46) || (int) c == 44)
                  || (int) c == 58) || (int) c == 59) || (int) c == 60)
               || (int) c == 62) || (int) c == 34) || (int) c == 92)
            || (int) c == 39) != 0)
     foo();
 }

into:

define i32 @crud(i8 zeroext %c, i32 %x) nounwind ssp noredzone {
entry:
  %cmp = icmp ult i8 %c, 33
  br i1 %cmp, label %if.then, label %switch.early.test

switch.early.test:                                ; preds = %entry
  switch i8 %c, label %if.end [
    i8 39, label %if.then
    i8 44, label %if.then
    i8 58, label %if.then
    i8 59, label %if.then
    i8 60, label %if.then
    i8 62, label %if.then
    i8 46, label %if.then
    i8 92, label %if.then
    i8 34, label %if.then
  ]

by pulling the < comparison out ahead of the newly formed switch.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121680 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner
2010-12-13 04:50:38 +00:00
parent f5198e7fe3
commit 7312a22ed6
2 changed files with 69 additions and 4 deletions
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test/Transforms/SimplifyCFG/switch_create.ll
+24 -1
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@@ -149,7 +149,30 @@ UnifiedReturnBlock: ; preds = %shortcirc_done.4, %shortcirc_next.4
; CHECK: i32 18, label %UnifiedReturnBlock
; CHECK: i32 19, label %switch.edge
; CHECK: ]
}
define void @test7(i8 zeroext %c, i32 %x) nounwind ssp noredzone {
entry:
%cmp = icmp ult i32 %x, 32
%cmp4 = icmp eq i8 %c, 97
%or.cond = or i1 %cmp, %cmp4
%cmp9 = icmp eq i8 %c, 99
%or.cond11 = or i1 %or.cond, %cmp9
br i1 %or.cond11, label %if.then, label %if.end
if.then: ; preds = %entry
tail call void @foo1() nounwind noredzone
ret void
if.end: ; preds = %entry
ret void
; CHECK: @test7
; CHECK: %cmp = icmp ult i32 %x, 32
; CHECK: br i1 %cmp, label %if.then, label %switch.early.test
; CHECK: switch.early.test:
; CHECK: switch i8 %c, label %if.end [
; CHECK: i8 99, label %if.then
; CHECK: i8 97, label %if.then
; CHECK: ]
}