[InstCombine] Increase recursion limit to 3 in simplifyNonNullOperand

Author: dtcxzyw

llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp

@@ -996,7 +996,8 @@ Value *InstCombinerImpl::simplifyNonNullOperand(Value *V,
   if (!V->hasOneUse())
     return nullptr;
 
-  if (Depth == 1)
+  constexpr unsigned RecursionLimit = 3;
+  if (Depth == RecursionLimit)
     return nullptr;
 
   if (auto *GEP = dyn_cast<GetElementPtrInst>(V)) {

llvm/test/Transforms/InstCombine/load.ll

@@ -454,8 +454,7 @@ define i32 @load_select_with_null_gep(i1 %cond, ptr %p, i64 %off) {
 
 define i16 @load_select_with_null_gep2(i1 %cond, ptr %p, i64 %x) {
 ; CHECK-LABEL: @load_select_with_null_gep2(
-; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[COND:%.*]], ptr [[P:%.*]], ptr null
-; CHECK-NEXT:    [[INVARIANT_GEP:%.*]] = getelementptr i8, ptr [[SEL]], i64 -2
+; CHECK-NEXT:    [[INVARIANT_GEP:%.*]] = getelementptr i8, ptr [[SEL:%.*]], i64 -2
 ; CHECK-NEXT:    [[GEP:%.*]] = getelementptr i16, ptr [[INVARIANT_GEP]], i64 [[X:%.*]]
 ; CHECK-NEXT:    [[RES:%.*]] = load i16, ptr [[GEP]], align 2
 ; CHECK-NEXT:    ret i16 [[RES]]
@@ -469,8 +468,7 @@ define i16 @load_select_with_null_gep2(i1 %cond, ptr %p, i64 %x) {
 
 define i16 @load_select_with_null_ge3(i1 %cond, ptr %p, i64 %x, i64 %y) {
 ; CHECK-LABEL: @load_select_with_null_ge3(
-; CHECK-NEXT:    [[SEL:%.*]] = select i1 [[COND:%.*]], ptr [[P:%.*]], ptr null
-; CHECK-NEXT:    [[INVARIANT_GEP:%.*]] = getelementptr i8, ptr [[SEL]], i64 -2
+; CHECK-NEXT:    [[INVARIANT_GEP:%.*]] = getelementptr i8, ptr [[SEL:%.*]], i64 -2
 ; CHECK-NEXT:    [[GEP:%.*]] = getelementptr i16, ptr [[INVARIANT_GEP]], i64 [[X:%.*]]
 ; CHECK-NEXT:    [[GEP2:%.*]] = getelementptr i16, ptr [[GEP]], i64 [[Y:%.*]]
 ; CHECK-NEXT:    [[RES:%.*]] = load i16, ptr [[GEP2]], align 2