[llvm] (Draft) [SimplifyIndVar] Push more users to worklist for simplifyUsers (PR #93598)

[via llvm-commits]

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@@ -511,6 +511,7 @@ bool SimplifyIndvar::eliminateTrunc(TruncInst *TI) {
     ICmpInst *ICI = dyn_cast<ICmpInst>(U);
     if (!ICI) return false;
     assert(L->contains(ICI->getParent()) && "LCSSA form broken?");
+    //    assert(L->contains(ICI->getParent()) && "LCSSA form broken?");
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v01dXYZ wrote:

This check will break if there is an exit (or dominated) block with a use-chain `trunc-icmp` such as the following one from `Bitcode/Regression/fft/x86_17.06.19_halide_runtime.bc halide_memoization_cache_lookup`: 

``` llvm
for.cond82.preheader:                             ; preds = %_ZNK15halide_buffer_t13size_in_bytesEv.exit
  %48 = trunc i64 %indvars.iv214 to i32
  %cmp83195 = icmp sgt i32 %48, 0
  br i1 %cmp83195, label %for.body85.preheader, label %cleanup111
```

or such as:

``` llvm
define i1 @foo(i32 %n) {
entry:
    br label %loop

loop:
    %i = phi i64 [0, %entry], [%i.inc, %loop]
    %i.inc = add i64 %i, 1

    %i.ult.Icnt = icmp ult i64 %i, 128

    br i1 %i.ult.Icnt, label %loop, label %loop.exit

loop.exit:
    %i.32 = trunc i64 %i to i32
    %i.32.ult.n = icmp ult i32 %i.32, %n
    ret i1 %i.32.ult.n
}
```

I've got to take a closer look at the code to understand why LCSSA is required here.

https://github.com/llvm/llvm-project/pull/93598