[llvm] r368715 - [SLC] Improve dereferenceable bytes annotation

[David Bolvansky via llvm-commits]

Author: xbolva00
Date: Tue Aug 13 09:44:16 2019
New Revision: 368715

URL: http://llvm.org/viewvc/llvm-project?rev=368715&view=rev
Log:
[SLC] Improve dereferenceable bytes annotation

Modified:
    llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp
    llvm/trunk/test/Transforms/InstCombine/mem-deref-bytes.ll

Modified: llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp?rev=368715&r1=368714&r2=368715&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp (original)
+++ llvm/trunk/lib/Transforms/Utils/SimplifyLibCalls.cpp Tue Aug 13 09:44:16 2019
@@ -188,8 +188,12 @@ static bool canTransformToMemCmp(CallIns
 
 static void annotateDereferenceableBytes(CallInst *CI,
                                          ArrayRef<unsigned> ArgNos,
-                                         uint64_t DerefBytes) {
+                                         uint64_t DereferenceableBytes) {
   for (unsigned ArgNo : ArgNos) {
+    uint64_t DerefBytes = std::max(
+        CI->getDereferenceableOrNullBytes(ArgNo + AttributeList::FirstArgIndex),
+        DereferenceableBytes);
+
     if (CI->getDereferenceableBytes(ArgNo + AttributeList::FirstArgIndex) <
         DerefBytes) {
       CI->removeParamAttr(ArgNo, Attribute::Dereferenceable);

Modified: llvm/trunk/test/Transforms/InstCombine/mem-deref-bytes.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/mem-deref-bytes.ll?rev=368715&r1=368714&r2=368715&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/mem-deref-bytes.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/mem-deref-bytes.ll Tue Aug 13 09:44:16 2019
@@ -48,7 +48,7 @@ define i32 @memcmp_const_size_no_update_
 
 define i32 @memcmp_const_size_no_update_deref2(i8* nocapture readonly %d, i8* nocapture readonly %s) {
 ; CHECK-LABEL: @memcmp_const_size_no_update_deref2(
-; CHECK-NEXT:    [[CALL:%.*]] = tail call i32 @memcmp(i8* dereferenceable(16) [[D:%.*]], i8* dereferenceable(16) [[S:%.*]], i64 16)
+; CHECK-NEXT:    [[CALL:%.*]] = tail call i32 @memcmp(i8* dereferenceable(40) [[D:%.*]], i8* dereferenceable(16) [[S:%.*]], i64 16)
 ; CHECK-NEXT:    ret i32 [[CALL]]
 ;
   %call = tail call i32 @memcmp(i8* dereferenceable_or_null(40) %d, i8* %s, i64 16)