[llvm] [Loads] Support dereferenceable assumption with variable size. (PR #128436)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `llvm-clang-x86_64-sie-win` running on `sie-win-worker` while building `llvm` at step 7 "test-build-unified-tree-check-all".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/46/builds/20029

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 7 (test-build-unified-tree-check-all) failure: test (failure)
******************** TEST 'LLVM :: Transforms/LoopVectorize/vect.stats.ll' FAILED ********************
Exit Code: 1

Command Output (stdout):
--
# RUN: at line 1
z:\b\llvm-clang-x86_64-sie-win\build\bin\opt.exe < Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm\test\Transforms\LoopVectorize\vect.stats.ll -passes=loop-vectorize -force-vector-interleave=4 -force-vector-width=4 -debug-only=loop-vectorize -enable-early-exit-vectorization --disable-output -stats -S 2>&1 | z:\b\llvm-clang-x86_64-sie-win\build\bin\filecheck.exe Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm\test\Transforms\LoopVectorize\vect.stats.ll
# executed command: 'z:\b\llvm-clang-x86_64-sie-win\build\bin\opt.exe' -passes=loop-vectorize -force-vector-interleave=4 -force-vector-width=4 -debug-only=loop-vectorize -enable-early-exit-vectorization --disable-output -stats -S
# note: command had no output on stdout or stderr
# executed command: 'z:\b\llvm-clang-x86_64-sie-win\build\bin\filecheck.exe' 'Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm\test\Transforms\LoopVectorize\vect.stats.ll'
# .---command stderr------------
# | Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm\test\Transforms\LoopVectorize\vect.stats.ll:8:10: error: CHECK: expected string not found in input
# | ; CHECK: 1 loop-vectorize - Number of early exit loops vectorized
# |          ^
# | <stdin>:260:62: note: scanning from here
# | 3 loop-vectorize - Number of loops analyzed for vectorization
# |                                                              ^
# | <stdin>:261:1: note: possible intended match here
# | 1 loop-vectorize - Number of loops vectorized
# | ^
# | 
# | Input file: <stdin>
# | Check file: Z:\b\llvm-clang-x86_64-sie-win\llvm-project\llvm\test\Transforms\LoopVectorize\vect.stats.ll
# | 
# | -dump-input=help explains the following input dump.
# | 
# | Input was:
# | <<<<<<
# |            1:  
# |            2: LV: Checking a loop in 'vectorized' from <stdin> 
# |            3: LV: Loop hints: force=? width=4 interleave=4 
# |            4: LV: Found a loop: for.body 
# |            5: LV: Found an induction variable. 
# |            6: LV: Found FP op with unsafe algebra. 
# |            7: LV: We can vectorize this loop! 
# |            8: LV: Loop does not require scalar epilogue 
# |            9: LV: Found trip count: 0 
# |           10: LV: The max safe fixed VF is: 67108864. 
# |           11: LV: The max safe scalable VF is: vscale x 0. 
# |           12: LV: Found uniform instruction: %cmp2 = icmp sgt i64 %indvars.iv.next, %size 
# |           13: LV: Found uniform instruction: %arrayidx = getelementptr inbounds float, ptr %a, i64 %indvars.iv2 
# |           14: LV: Found uniform instruction: %indvars.iv2 = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %for.body.preheader ] 
# |           15: LV: Found uniform instruction: %indvars.iv.next = add nuw nsw i64 %indvars.iv2, 1 
# |           16: LV: Found scalar instruction: %indvars.iv2 = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %for.body.preheader ] 
# |           17: LV: Found scalar instruction: %indvars.iv.next = add nuw nsw i64 %indvars.iv2, 1 
# |           18: LV: Found an estimated cost of 1 for VF 4 For instruction: %indvars.iv2 = phi i64 [ %indvars.iv.next, %for.body ], [ 0, %for.body.preheader ] 
# |           19: LV: Found an estimated cost of 0 for VF 4 For instruction: %arrayidx = getelementptr inbounds float, ptr %a, i64 %indvars.iv2 
# |           20: LV: Found an estimated cost of 1 for VF 4 For instruction: %0 = load float, ptr %arrayidx, align 4 
# |           21: LV: Found an estimated cost of 1 for VF 4 For instruction: %mul = fmul float %0, %0 
# |           22: LV: Found an estimated cost of 1 for VF 4 For instruction: store float %mul, ptr %arrayidx, align 4 
...

```

</details>

https://github.com/llvm/llvm-project/pull/128436