[llvm] [X86][SimplifyCFG] Support hoisting load/store with conditional faulting (PR #96878)

[Yingwei Zheng via llvm-commits]

dtcxzyw wrote:

@KanRobert Can you file a separate PR to support conditional load/store of ptrs with +cf? Then I can share another miscompilation reproducer :)
```
@e = dso_local global ptr null, align 8
@f = dso_local global ptr @e, align 8
@g = dso_local global ptr @f, align 8
@h = dso_local global ptr @g, align 8
@d = dso_local global i8 0, align 1
@.str = private unnamed_addr constant [4 x i8] c"%d\0A\00", align 1
@c = dso_local global i64 0, align 8

; Function Attrs: nounwind uwtable
define dso_local void @i() #0 {
entry:
  %p = alloca i32, align 4
  call void @llvm.lifetime.start.p0(i64 4, ptr %p) #3
  store i8 0, ptr @d, align 1
  br label %for.cond

for.cond:                                         ; preds = %for.inc, %entry
  %0 = load i8, ptr @d, align 1
  %conv = sext i8 %0 to i32
  %cmp = icmp slt i32 %conv, 2
  br i1 %cmp, label %for.body, label %for.end

for.body:                                         ; preds = %for.cond
  %1 = load ptr, ptr @h, align 8
  %2 = load ptr, ptr %1, align 8
  %3 = load ptr, ptr %2, align 8
  %4 = load ptr, ptr %3, align 8
  %5 = load ptr, ptr @f, align 8
  store ptr %4, ptr %5, align 8
  %6 = load ptr, ptr @h, align 8
  %7 = load ptr, ptr %6, align 8
  %8 = load ptr, ptr %7, align 8
  store ptr %4, ptr %8, align 8
  br label %for.inc

for.inc:                                          ; preds = %for.body
  %9 = load i8, ptr @d, align 1
  %inc = add i8 %9, 1
  store i8 %inc, ptr @d, align 1
  br label %for.cond

for.end:                                          ; preds = %for.cond
  store i32 0, ptr %p, align 4
  br label %for.cond2

for.cond2:                                        ; preds = %for.body3, %for.end
  %10 = load i32, ptr %p, align 4
  %tobool = icmp ne i32 %10, 0
  br i1 %tobool, label %for.body3, label %for.end4

for.body3:                                        ; preds = %for.cond2
  br label %for.cond2

for.end4:                                         ; preds = %for.cond2
  call void @llvm.lifetime.end.p0(i64 4, ptr %p)
  ret void
}

; Function Attrs: nounwind uwtable
define dso_local signext i32 @main() #0 {
entry:
  %retval = alloca i32, align 4
  store i32 0, ptr %retval, align 4
  call void @i()
  %0 = load i64, ptr @c, align 8
  %conv = trunc i64 %0 to i32
  %call = call signext i32 (ptr, ...) @printf(ptr noundef @.str, i32 noundef signext %conv)
  ret i32 0
}

declare noundef signext i32 @printf(ptr nocapture noundef readonly, ...)
```



https://github.com/llvm/llvm-project/pull/96878