Reintroduce "[SCCP] Propagate integer range info for parameters in IPSCCP."

Description

Reintroduce "[SCCP] Propagate integer range info for parameters in IPSCCP."

This is r315288 & r315294, which were reverted due to stage2 bot
failures.

Summary:
This updates the SCCP solver to use of the ValueElement lattice for
parameters, which provides integer range information. The range
information is used to remove unneeded icmp instructions.

For the following function, f() can be optimized to ret i32 2 with
this change

source_filename = "sccp.c"
target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"

; Function Attrs: norecurse nounwind readnone uwtable
define i32 @main() local_unnamed_addr #0 {
entry:
  %call = tail call fastcc i32 @f(i32 1)
  %call1 = tail call fastcc i32 @f(i32 47)
  %add3 = add nsw i32 %call, %call1
  ret i32 %add3
}

; Function Attrs: noinline norecurse nounwind readnone uwtable
define internal fastcc i32 @f(i32 %x) unnamed_addr #1 {
entry:
  %c1 = icmp sle i32 %x, 100

  %cmp = icmp sgt i32 %x, 300
  %. = select i1 %cmp, i32 1, i32 2
  ret i32 %.
}

attributes #1 = { noinline }

Reviewers: davide, sanjoy, efriedma, dberlin

Reviewed By: davide, dberlin

Subscribers: mcrosier, gberry, mssimpso, dberlin, llvm-commits

Differential Revision: https://reviews.llvm.org/D36656

Details

Committed
brunoOct 12 2017, 9:54 AM
Reviewer
davide
Differential Revision
D36656: [SCCP] Propagate integer range info for parameters in IPSCCP.
Parents
rL315592: [PowerPC] Add profitablilty check for conversion to mtctr loops
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