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llvm-6502/test/CodeGen/X86/loop-strength-reduce3.ll
Evan Cheng cdf43b1fad If a loop termination compare instruction is the only use of its stride,
and the compaison is against a constant value, try eliminate the stride
by moving the compare instruction to another stride and change its
constant operand accordingly. e.g.

loop:
...
v1 = v1 + 3
v2 = v2 + 1
if (v2 < 10) goto loop
=>
loop:
...
v1 = v1 + 3
if (v1 < 30) goto loop


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43336 91177308-0d34-0410-b5e6-96231b3b80d8
2007-10-25 09:11:16 +00:00

38 lines
1.8 KiB
LLVM

; RUN: llvm-as < %s | llc -march=x86 | grep cmp | grep 240
; RUN: llvm-as < %s | llc -march=x86 | grep inc | count 1
define i32 @foo(i32 %A, i32 %B, i32 %C, i32 %D) {
entry:
%tmp2955 = icmp sgt i32 %C, 0 ; <i1> [#uses=1]
br i1 %tmp2955, label %bb26.outer.us, label %bb40.split
bb26.outer.us: ; preds = %bb26.bb32_crit_edge.us, %entry
%i.044.0.ph.us = phi i32 [ 0, %entry ], [ %indvar.next57, %bb26.bb32_crit_edge.us ] ; <i32> [#uses=2]
%k.1.ph.us = phi i32 [ 0, %entry ], [ %k.0.us, %bb26.bb32_crit_edge.us ] ; <i32> [#uses=1]
%tmp3.us = mul i32 %i.044.0.ph.us, 6 ; <i32> [#uses=1]
br label %bb1.us
bb1.us: ; preds = %bb1.us, %bb26.outer.us
%j.053.us = phi i32 [ 0, %bb26.outer.us ], [ %tmp25.us, %bb1.us ] ; <i32> [#uses=2]
%k.154.us = phi i32 [ %k.1.ph.us, %bb26.outer.us ], [ %k.0.us, %bb1.us ] ; <i32> [#uses=1]
%tmp5.us = add i32 %tmp3.us, %j.053.us ; <i32> [#uses=1]
%tmp7.us = shl i32 %D, %tmp5.us ; <i32> [#uses=2]
%tmp9.us = icmp eq i32 %tmp7.us, %B ; <i1> [#uses=1]
%tmp910.us = zext i1 %tmp9.us to i32 ; <i32> [#uses=1]
%tmp12.us = and i32 %tmp7.us, %A ; <i32> [#uses=1]
%tmp19.us = and i32 %tmp12.us, %tmp910.us ; <i32> [#uses=1]
%k.0.us = add i32 %tmp19.us, %k.154.us ; <i32> [#uses=3]
%tmp25.us = add i32 %j.053.us, 1 ; <i32> [#uses=2]
%tmp29.us = icmp slt i32 %tmp25.us, %C ; <i1> [#uses=1]
br i1 %tmp29.us, label %bb1.us, label %bb26.bb32_crit_edge.us
bb26.bb32_crit_edge.us: ; preds = %bb1.us
%indvar.next57 = add i32 %i.044.0.ph.us, 1 ; <i32> [#uses=2]
%exitcond = icmp eq i32 %indvar.next57, 40 ; <i1> [#uses=1]
br i1 %exitcond, label %bb40.split, label %bb26.outer.us
bb40.split: ; preds = %bb26.bb32_crit_edge.us, %entry
%k.1.lcssa.lcssa.us-lcssa = phi i32 [ %k.0.us, %bb26.bb32_crit_edge.us ], [ 0, %entry ] ; <i32> [#uses=1]
ret i32 %k.1.lcssa.lcssa.us-lcssa
}