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Summary: Currently we express umin as `~umax(~x, ~y)`. However, this becomes a problem for operands in non-integral pointer spaces, because `~x` is not something we can compute for `x` non-integral. However, since comparisons are generally still allowed, we are actually able to express `umin(x, y)` directly as long as we don't try to express is as a umax. Support this by adding an explicit umin/smin representation to SCEV. We do this by factoring the existing getUMax/getSMax functions into a new function that does all four. The previous two functions were largely identical. Reviewed By: sanjoy Differential Revision: https://reviews.llvm.org/D50167 llvm-svn: 360159
27 lines
801 B
LLVM
27 lines
801 B
LLVM
; RUN: opt < %s -analyze -scalar-evolution \
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; RUN: -scalar-evolution-max-iterations=0 | FileCheck %s
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; PR2607
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define i32 @b(i32 %x, i32 %y) nounwind {
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entry:
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%cmp2 = icmp slt i32 %y, %x
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%cond3 = select i1 %cmp2, i32 %y, i32 %x
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%cmp54 = icmp slt i32 %cond3, -2147483632
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br i1 %cmp54, label %forinc, label %afterfor
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forinc: ; preds = %forinc, %entry
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%j.01 = phi i32 [ %dec, %forinc ], [ -2147483632, %entry ]
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%dec = add i32 %j.01, -1
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%cmp = icmp slt i32 %y, %x
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%cond = select i1 %cmp, i32 %y, i32 %x
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%cmp5 = icmp sgt i32 %dec, %cond
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br i1 %cmp5, label %forinc, label %afterfor
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afterfor: ; preds = %forinc, %entry
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%j.0.lcssa = phi i32 [ -2147483632, %entry ], [ %dec, %forinc ]
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ret i32 %j.0.lcssa
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}
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; CHECK: backedge-taken count is (-2147483633 + (-1 * (%{{[xy]}} smin %{{[xy]}})))
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