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llvm-project/llvm/test/Transforms/LoopStrengthReduce/lsr-expand-quadratic.ll

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Fix SCEVExpander: don't try to expand quadratic recurrences outside a loop. Partial fix for PR17459: wrong code at -O3 on x86_64-linux-gnu (affecting trunk and 3.3) When SCEV expands a recurrence outside of a loop it attempts to scale by the stride of the recurrence. Chained recurrences don't work that way. We could compute binomial coefficients, but would hve to guarantee that the chained AddRec's are in a perfectly reduced form. llvm-svn: 193438
2013-10-26 05:35:56 +08:00
; RUN: opt -loop-reduce -S < %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-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx"
; PR15470: LSR miscompile. The test2 function should return '1'.
;
; SCEV expander cannot expand quadratic recurrences outside of the
; loop. This recurrence depends on %sub.us, so can't be expanded.
;
; CHECK-LABEL: @test2
; CHECK-LABEL: test2.loop:
; CHECK: %lsr.iv = phi i32 [ %lsr.iv.next, %test2.loop ], [ -16777216, %entry ]
; CHECK: %lsr.iv.next = add nsw i32 %lsr.iv, 16777216
;
Fix broken CHECK lines. llvm-svn: 199016
2014-01-12 05:06:00 +08:00
; CHECK-LABEL: for.end:
Fix SCEVExpander: don't try to expand quadratic recurrences outside a loop. Partial fix for PR17459: wrong code at -O3 on x86_64-linux-gnu (affecting trunk and 3.3) When SCEV expands a recurrence outside of a loop it attempts to scale by the stride of the recurrence. Chained recurrences don't work that way. We could compute binomial coefficients, but would hve to guarantee that the chained AddRec's are in a perfectly reduced form. llvm-svn: 193438
2013-10-26 05:35:56 +08:00
; CHECK: %sub.cond.us = sub nsw i32 %inc1115.us, %sub.us
; CHECK: %sext.us = mul i32 %lsr.iv.next, %sub.cond.us
; CHECK: %f = ashr i32 %sext.us, 24
; CHECK: ret i32 %f
define i32 @test2() {
entry:
br label %test2.loop
test2.loop:
%inc1115.us = phi i32 [ 0, %entry ], [ %inc11.us, %test2.loop ]
%inc11.us = add nsw i32 %inc1115.us, 1
%cmp.us = icmp slt i32 %inc11.us, 2
br i1 %cmp.us, label %test2.loop, label %for.end
for.end:
%tobool.us = icmp eq i32 %inc1115.us, 0
%sub.us = select i1 %tobool.us, i32 0, i32 0
%mul.us = shl i32 %inc1115.us, 24
%sub.cond.us = sub nsw i32 %inc1115.us, %sub.us
%sext.us = mul i32 %mul.us, %sub.cond.us
%f = ashr i32 %sext.us, 24
br label %exit
exit:
ret i32 %f
}