codgen: make the Memory GEP an inbounds GEP (#55107)

The Julia memory model is always inbounds for GEP.

This makes the code in #55090
look almost the same as it did before the change. Locally I wasn't able
to reproduce the regression, but given it's vectorized code I suspect it
is backend sensitive.

Fixes #55090

Co-authored-by: Zentrik <[email protected]>

Author: gbaraldi

src/cgutils.cpp

@@ -4286,9 +4286,8 @@ static jl_cgval_t emit_memoryref(jl_codectx_t &ctx, const jl_cgval_t &ref, jl_cg
             ovflw = ctx.builder.CreateICmpUGE(ctx.builder.CreateAdd(offset, mlen), ctx.builder.CreateNUWAdd(mlen, mlen));
         }
 #endif
-        //Is this change fine
         boffset = ctx.builder.CreateMul(offset, elsz);
-        newdata = ctx.builder.CreateGEP(getInt8Ty(ctx.builder.getContext()), data, boffset);
+        newdata = ctx.builder.CreateInBoundsGEP(getInt8Ty(ctx.builder.getContext()), data, boffset);
         (void)boffset; // LLVM is very bad at handling GEP with types different from the load
         if (bc) {
             BasicBlock *failBB, *endBB;