[PATCH] D66161: [SLC] Dereferenceable annonation - handle valid null pointers

[Dávid Bolvanský via Phabricator via llvm-commits]

xbolva00 updated this revision to Diff 214911.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D66161/new/

https://reviews.llvm.org/D66161

Files:
  lib/Transforms/Utils/SimplifyLibCalls.cpp
  test/Transforms/InstCombine/mem-deref-bytes.ll


Index: test/Transforms/InstCombine/mem-deref-bytes.ll
===================================================================
--- test/Transforms/InstCombine/mem-deref-bytes.ll
+++ test/Transforms/InstCombine/mem-deref-bytes.ll
@@ -55,7 +55,7 @@
   ret i32 %call
 }
 
-define i32 @memcmp_const_size_update_deref5(i8* nocapture readonly %d, i8* nocapture readonly %s) {
+define i32 @memcmp_const_size_update_deref5(i8* nocapture readonly %d, i8* nocapture readonly %s) "null-pointer-is-valid"="false" {
 ; CHECK-LABEL: @memcmp_const_size_update_deref5(
 ; CHECK-NEXT:    [[CALL:%.*]] = tail call i32 @memcmp(i8* dereferenceable(40) [[D:%.*]], i8* dereferenceable(16) [[S:%.*]], i64 16)
 ; CHECK-NEXT:    ret i32 [[CALL]]
@@ -64,8 +64,17 @@
   ret i32 %call
 }
 
-define i32 @memcmp_const_size_no_update_deref(i8* nocapture readonly %d, i8* nocapture readonly %s) {
+define i32 @memcmp_const_size_no_update_deref(i8* nocapture readonly %d, i8* nocapture readonly %s) "null-pointer-is-valid"="true" {
 ; CHECK-LABEL: @memcmp_const_size_no_update_deref(
+; CHECK-NEXT:    [[CALL:%.*]] = tail call i32 @memcmp(i8* dereferenceable(16) [[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)
+  ret i32 %call
+}
+
+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(40) [[D:%.*]], i8* dereferenceable(20) [[S:%.*]], i64 16)
 ; CHECK-NEXT:    ret i32 [[CALL]]
 ;
Index: lib/Transforms/Utils/SimplifyLibCalls.cpp
===================================================================
--- lib/Transforms/Utils/SimplifyLibCalls.cpp
+++ lib/Transforms/Utils/SimplifyLibCalls.cpp
@@ -189,10 +189,15 @@
 static void annotateDereferenceableBytes(CallInst *CI,
                                          ArrayRef<unsigned> ArgNos,
                                          uint64_t DereferenceableBytes) {
+  Function *F = CI->getFunction();
+  if (!F)
+    return;
   for (unsigned ArgNo : ArgNos) {
-    uint64_t DerefBytes = std::max(
-        CI->getDereferenceableOrNullBytes(ArgNo + AttributeList::FirstArgIndex),
-        DereferenceableBytes);
+    uint64_t DerefBytes = DereferenceableBytes;
+    if (!F->nullPointerIsDefined())
+      DerefBytes = std::max(CI->getDereferenceableOrNullBytes(
+                                ArgNo + AttributeList::FirstArgIndex),
+                            DereferenceableBytes);
 
     if (CI->getDereferenceableBytes(ArgNo + AttributeList::FirstArgIndex) <
         DerefBytes) {


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