[llvm] [FunctionAttrs] Add the "initializes" attribute inference (PR #97373)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-armv8-quick` running on `linaro-clang-armv8-quick` while building `llvm` at step 5 "ninja check 1".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/154/builds/7675

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

```
Step 5 (ninja check 1) failure: stage 1 checked (failure)
******************** TEST 'Clang :: CodeGen/math-libcalls-tbaa-indirect-args.c' FAILED ********************
Exit Code: 1

Command Output (stderr):
--
RUN: at line 2: /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/clang -cc1 -internal-isystem /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/lib/clang/20/include -nostdsysteminc /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/math-libcalls-tbaa-indirect-args.c -O3 -fmath-errno -emit-llvm -triple x86_64-unknown-unknown -o - | /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/math-libcalls-tbaa-indirect-args.c -check-prefixes=CHECK
+ /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/math-libcalls-tbaa-indirect-args.c -check-prefixes=CHECK
+ /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/clang -cc1 -internal-isystem /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/lib/clang/20/include -nostdsysteminc /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/math-libcalls-tbaa-indirect-args.c -O3 -fmath-errno -emit-llvm -triple x86_64-unknown-unknown -o -
RUN: at line 3: /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/clang -cc1 -internal-isystem /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/lib/clang/20/include -nostdsysteminc /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/math-libcalls-tbaa-indirect-args.c -O3 -fmath-errno -emit-llvm -triple x86_64-pc-win64 -o - | /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/math-libcalls-tbaa-indirect-args.c -check-prefixes=CHECK-WIN64
+ /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/math-libcalls-tbaa-indirect-args.c -check-prefixes=CHECK-WIN64
+ /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/clang -cc1 -internal-isystem /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/lib/clang/20/include -nostdsysteminc /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/math-libcalls-tbaa-indirect-args.c -O3 -fmath-errno -emit-llvm -triple x86_64-pc-win64 -o -
RUN: at line 4: /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/clang -cc1 -internal-isystem /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/lib/clang/20/include -nostdsysteminc /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/math-libcalls-tbaa-indirect-args.c -O3 -fmath-errno -emit-llvm -triple i686-unknown-unknown -o - | /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/math-libcalls-tbaa-indirect-args.c -check-prefixes=CHECK-I686
+ /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/clang -cc1 -internal-isystem /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/lib/clang/20/include -nostdsysteminc /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/math-libcalls-tbaa-indirect-args.c -O3 -fmath-errno -emit-llvm -triple i686-unknown-unknown -o -
+ /home/tcwg-buildbot/worker/clang-armv8-quick/stage1/bin/FileCheck /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/math-libcalls-tbaa-indirect-args.c -check-prefixes=CHECK-I686
/home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/math-libcalls-tbaa-indirect-args.c:86:21: error: CHECK-I686-SAME: expected string not found in input
// CHECK-I686-SAME: ptr dead_on_unwind noalias nocapture writable writeonly sret({ x86_fp80, x86_fp80 }) align 4 [[AGG_RESULT:%.*]], ptr nocapture noundef readonly byval({ x86_fp80, x86_fp80 }) align 4 [[CLD:%.*]]) local_unnamed_addr #[[ATTR2:[0-9]+]] {
                    ^
<stdin>:17:35: note: scanning from here
define dso_local void @test_cargl(ptr dead_on_unwind noalias nocapture writable writeonly sret({ x86_fp80, x86_fp80 }) align 4 initializes((0, 10), (12, 22)) %agg.result, ptr nocapture noundef readonly byval({ x86_fp80, x86_fp80 }) align 4 %cld) local_unnamed_addr #2 {
                                  ^

Input file: <stdin>
Check file: /home/tcwg-buildbot/worker/clang-armv8-quick/llvm/clang/test/CodeGen/math-libcalls-tbaa-indirect-args.c

-dump-input=help explains the following input dump.

Input was:
<<<<<<
         .
         .
         .
        12:  
        13: ; Function Attrs: mustprogress nofree nounwind willreturn memory(write) 
        14: declare x86_fp80 @powl(x86_fp80 noundef, x86_fp80 noundef) local_unnamed_addr #1 
        15:  
        16: ; Function Attrs: nounwind 
        17: define dso_local void @test_cargl(ptr dead_on_unwind noalias nocapture writable writeonly sret({ x86_fp80, x86_fp80 }) align 4 initializes((0, 10), (12, 22)) %agg.result, ptr nocapture noundef readonly byval({ x86_fp80, x86_fp80 }) align 4 %cld) local_unnamed_addr #2 { 
same:86                                       X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found
        18: entry: 
same:86     ~~~~~~~
        19:  %byval-temp = alloca { x86_fp80, x86_fp80 }, align 4 
same:86     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        20:  %cld.real = load x86_fp80, ptr %cld, align 4 
same:86     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        21:  %cld.imagp = getelementptr inbounds nuw i8, ptr %cld, i32 12 
same:86     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
        22:  %cld.imag = load x86_fp80, ptr %cld.imagp, align 4 
same:86     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
         .
         .
...

```

</details>

https://github.com/llvm/llvm-project/pull/97373