[llvm] [LoongArch][ISel] Check the number of sign bits in `PatGprGpr_32` (PR #107432)

[via llvm-commits]

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@@ -189,8 +189,6 @@ define signext i32 @sdiv_si32_ui32_ui32(i32 %a, i32 %b) {
 ;
 ; LA64-LABEL: sdiv_si32_ui32_ui32:
 ; LA64:       # %bb.0: # %entry
-; LA64-NEXT:    addi.w $a1, $a1, 0
----------------
wangleiat wrote:

We should be more careful with division. for example:
```
define signext i32 @foo(i32 signext %a, i32 signext %b)  {
entry:                                                                                                           
  %conv = sext i32 %a to i64                                                                                     
  %conv1 = sext i32 %b to i64                                                                                    
  %div = sdiv i64 %conv1, %conv                                                                                  
  %conv2 = trunc i64 %div to i32                                                                                 
  ret i32 %conv2                                                                                                 
}                                                                                                                
```
In some cases this may not be possible using 32-bit division either.

https://github.com/llvm/llvm-project/pull/107432