[InstCombineCalls] Use isKnownNonNullAt() to check nullness of gc.rel…

…ocate return value

Summary: This patch replaces isKnownNonNull() with isKnownNonNullAt() when checking nullness of gc.relocate return value. In this way it can handle cases where the relocated value does not have nonnull attribute but has a dominating null check from the CFG.

Reviewers: reames

Subscribers: llvm-commits, sanjoy

Differential Revision: http://reviews.llvm.org/D12772

llvm-svn: 247353

llvm/lib/Transforms/InstCombine/InstCombineCalls.cpp

@@ -1367,7 +1367,7 @@ Instruction *InstCombiner::visitCallInst(CallInst &CI) {
     }
 
     // isKnownNonNull -> nonnull attribute
-    if (isKnownNonNull(DerivedPtr))
+    if (isKnownNonNullAt(DerivedPtr, II, DT, TLI))
       II->addAttribute(AttributeSet::ReturnIndex, Attribute::NonNull);
 
     // isDereferenceablePointer -> deref attribute

llvm/test/Transforms/InstCombine/gc.relocate.ll

@@ -19,3 +19,34 @@ entry:
     %relocate = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32 %tok,  i32 7, i32 7)
     ret i32 addrspace(1)* %relocate
 }
+
+define i32 @explicit_nonnull(i32 addrspace(1)* nonnull %dparam) gc "statepoint-example" {
+; Checks that a nonnull pointer
+; CHECK-LABEL: @explicit_nonnull
+; CHECK: ret i32 1
+entry:
+    %load = load i32, i32 addrspace(1)* %dparam
+    %tok = tail call i32 (i64, i32, i1 ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_i1f(i64 0, i32 0, i1 ()* @return_i1, i32 0, i32 0, i32 0, i32 0, i32 addrspace(1)* %dparam)
+    %relocate = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32 %tok,  i32 7, i32 7)
+    %cmp = icmp eq i32 addrspace(1)* %relocate, null
+    %ret_val = select i1 %cmp, i32 0, i32 1
+    ret i32 %ret_val
+}
+
+define i32 @implicit_nonnull(i32 addrspace(1)* %dparam) gc "statepoint-example" {
+; Checks that a nonnull pointer
+; CHECK-LABEL: @implicit_nonnull
+; CHECK: ret i32 1
+entry:
+    %cond = icmp eq i32 addrspace(1)* %dparam, null
+    br i1 %cond, label %no_gc, label %gc
+gc:
+    %load = load i32, i32 addrspace(1)* %dparam
+    %tok = tail call i32 (i64, i32, i1 ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_i1f(i64 0, i32 0, i1 ()* @return_i1, i32 0, i32 0, i32 0, i32 0, i32 addrspace(1)* %dparam)
+    %relocate = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32 %tok,  i32 7, i32 7)
+    %cmp = icmp eq i32 addrspace(1)* %relocate, null
+    %ret_val = select i1 %cmp, i32 0, i32 1
+    ret i32 %ret_val
+no_gc:
+    unreachable
+}