[WasmEHPrepare] Explicitly create inbounds GEP (NFCI)

These are known to be inbounds, create them as such. NFCI because
constant expression construction currently already infers this.

Also drop the unnecessary zero-index GEP: This is equivalent to
the pointer itself nowadays.

Author: nikic

llvm/lib/CodeGen/WasmEHPrepare.cpp

@@ -252,12 +252,11 @@ bool WasmEHPrepareImpl::prepareEHPads(Function &F) {
       M.getOrInsertGlobal("__wasm_lpad_context", LPadContextTy));
   LPadContextGV->setThreadLocalMode(GlobalValue::GeneralDynamicTLSModel);
 
-  LPadIndexField = IRB.CreateConstGEP2_32(LPadContextTy, LPadContextGV, 0, 0,
-                                          "lpad_index_gep");
-  LSDAField =
-      IRB.CreateConstGEP2_32(LPadContextTy, LPadContextGV, 0, 1, "lsda_gep");
-  SelectorField = IRB.CreateConstGEP2_32(LPadContextTy, LPadContextGV, 0, 2,
-                                         "selector_gep");
+  LPadIndexField = LPadContextGV;
+  LSDAField = IRB.CreateConstInBoundsGEP2_32(LPadContextTy, LPadContextGV, 0, 1,
+                                             "lsda_gep");
+  SelectorField = IRB.CreateConstInBoundsGEP2_32(LPadContextTy, LPadContextGV,
+                                                 0, 2, "selector_gep");
 
   // wasm.landingpad.index() intrinsic, which is to specify landingpad index
   LPadIndexF = Intrinsic::getDeclaration(&M, Intrinsic::wasm_landingpad_index);