[llvm] [VPlan] First step towards VPlan cost modeling. (PR #92555)

[Arthur Eubanks via llvm-commits]

aeubanks wrote:

Another one with same error:
```
target datalayout = "e-m:o-p270:32:32-p271:32:32-p272:64:64-i64:64-i128:128-f80:128-n8:16:32:64-S128"
target triple = "x86_64-apple-macosx10.15.0"

define void @ff_mpadsp_init_x86_tabs(ptr %0, ptr %arrayidx47, ptr %arrayidx55) {
entry:
  br label %for.body3

for.body3:                                        ; preds = %for.body3, %entry
  %indvars.iv1 = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body3 ]
  %1 = load float, ptr null, align 4
  %2 = shl i64 %indvars.iv1, 2
  %arrayidx9 = getelementptr [4 x [160 x float]], ptr null, i64 0, i64 0, i64 %2
  store float 0.000000e+00, ptr %arrayidx9, align 4
  %3 = load float, ptr null, align 4
  %4 = or disjoint i64 %2, 1
  %arrayidx19 = getelementptr [4 x [160 x float]], ptr null, i64 0, i64 0, i64 %4
  store float 0.000000e+00, ptr %arrayidx19, align 4
  %5 = or disjoint i64 %2, 2
  %arrayidx29 = getelementptr [4 x [160 x float]], ptr null, i64 0, i64 0, i64 %5
  store float 0.000000e+00, ptr %arrayidx29, align 4
  %6 = or disjoint i64 %2, 3
  %arrayidx40 = getelementptr [4 x [160 x float]], ptr null, i64 0, i64 0, i64 %6
  store float 0.000000e+00, ptr %arrayidx40, align 4
  %7 = load float, ptr null, align 4
  store float 0.000000e+00, ptr %arrayidx47, align 4
  store float 0.000000e+00, ptr %arrayidx55, align 4
  store float 0.000000e+00, ptr %0, align 4
  %arrayidx76 = getelementptr [4 x [160 x float]], ptr %0, i64 0, i64 0, i64 %6
  store float 0.000000e+00, ptr %arrayidx76, align 4
  %indvars.iv.next = add i64 %indvars.iv1, 1
  %exitcond.not = icmp eq i64 %indvars.iv.next, 0
  br i1 %exitcond.not, label %for.inc77, label %for.body3

for.inc77:                                        ; preds = %for.body3
  ret void
}
```

https://github.com/llvm/llvm-project/pull/92555