llvm-6502/test/Transforms/IndVarSimplify/iv-fold.ll
Andrew Trick 06988bcf6a Made SCEV's UDiv expressions more canonical. When dividing a
recurrence, the initial values low bits can sometimes be ignored.

To take advantage of this, added FoldIVUser to IndVarSimplify to fold
an IV operand into a udiv/lshr if the operator doesn't affect the
result.

-indvars -disable-iv-rewrite now transforms

i = phi i4
i1 = i0 + 1
idx = i1 >> (2 or more)
i4 = i + 4

into

i = phi i4
idx = i0 >> ...
i4 = i + 4


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@137013 91177308-0d34-0410-b5e6-96231b3b80d8
2011-08-06 07:00:37 +00:00

57 lines
1.8 KiB
LLVM

; RUN: opt < %s -indvars -disable-iv-rewrite -S | FileCheck %s
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n:32:64"
; Indvars should be able to fold IV increments into shr when low bits are zero.
;
; CHECK: @foldIncShr
; CHECK: shr.1 = lshr i32 %0, 5
define i32 @foldIncShr(i32* %bitmap, i32 %bit_addr, i32 %nbits) nounwind {
entry:
br label %while.body
while.body:
%0 = phi i32 [ 0, %entry ], [ %inc.2, %while.body ]
%shr = lshr i32 %0, 5
%arrayidx = getelementptr inbounds i32* %bitmap, i32 %shr
%tmp6 = load i32* %arrayidx, align 4
%inc.1 = add i32 %0, 1
%shr.1 = lshr i32 %inc.1, 5
%arrayidx.1 = getelementptr inbounds i32* %bitmap, i32 %shr.1
%tmp6.1 = load i32* %arrayidx.1, align 4
%inc.2 = add i32 %inc.1, 1
%exitcond.3 = icmp eq i32 %inc.2, 128
br i1 %exitcond.3, label %while.end, label %while.body
while.end:
%r = add i32 %tmp6, %tmp6.1
ret i32 %r
}
; Invdars should not fold an increment into shr unless 2^shiftBits is
; a multiple of the recurrence step.
;
; CHECK: @noFoldIncShr
; CHECK: shr.1 = lshr i32 %inc.1, 5
define i32 @noFoldIncShr(i32* %bitmap, i32 %bit_addr, i32 %nbits) nounwind {
entry:
br label %while.body
while.body:
%0 = phi i32 [ 0, %entry ], [ %inc.3, %while.body ]
%shr = lshr i32 %0, 5
%arrayidx = getelementptr inbounds i32* %bitmap, i32 %shr
%tmp6 = load i32* %arrayidx, align 4
%inc.1 = add i32 %0, 1
%shr.1 = lshr i32 %inc.1, 5
%arrayidx.1 = getelementptr inbounds i32* %bitmap, i32 %shr.1
%tmp6.1 = load i32* %arrayidx.1, align 4
%inc.3 = add i32 %inc.1, 2
%exitcond.3 = icmp eq i32 %inc.3, 96
br i1 %exitcond.3, label %while.end, label %while.body
while.end:
%r = add i32 %tmp6, %tmp6.1
ret i32 %r
}