[PATCH] D12779: [InstCombineCalls] Use isKnownNonNullAt() to check nullness of passing arguments at callsite

[Chen Li via llvm-commits]

chenli created this revision.
chenli added a reviewer: reames.
chenli added a subscriber: llvm-commits.

This patch replaces isKnownNonNull() with isKnownNonNullAt() when checking nullness of passing arguments at callsite. In this way it can handle cases where the argument does not have nonnull attribute but has a dominating null check from the CFG.

http://reviews.llvm.org/D12779

Files:
  lib/Transforms/InstCombine/InstCombineCalls.cpp
  test/Transforms/InstCombine/call_nonnull_arg.ll

Index: test/Transforms/InstCombine/call_nonnull_arg.ll
===================================================================
--- /dev/null
+++ test/Transforms/InstCombine/call_nonnull_arg.ll
@@ -0,0 +1,17 @@
+; RUN: opt < %s -instcombine -S | FileCheck %s
+
+; InstCombine should mark null-checked argument as nonnull at callsite
+declare void @dummy(i32*)
+
+define void @test(i32* %a) {
+; CHECK-LABEL: @test
+; CHECK: call void @dummy(i32* nonnull %a)
+entry:
+  %cond = icmp eq i32* %a, null
+  br i1 %cond, label %is_null, label %not_null
+not_null:
+  call void @dummy(i32* %a)
+  ret void
+is_null:
+  unreachable
+}
Index: lib/Transforms/InstCombine/InstCombineCalls.cpp
===================================================================
--- lib/Transforms/InstCombine/InstCombineCalls.cpp
+++ lib/Transforms/InstCombine/InstCombineCalls.cpp
@@ -1537,7 +1537,7 @@
   unsigned ArgNo = 0;
   for (Value *V : CS.args()) {
     if (!CS.paramHasAttr(ArgNo+1, Attribute::NonNull) &&
-        isKnownNonNull(V)) {
+        isKnownNonNullAt(V, CS.getInstruction(), DT, TLI)) {
       AttributeSet AS = CS.getAttributes();
       AS = AS.addAttribute(CS.getInstruction()->getContext(), ArgNo+1,
                            Attribute::NonNull);


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