From: Yevgeny Rouban <yevgeny.rouban@azul.com>
Date: Mon, 21 Oct 2019 06:52:08 +0000 (+0000)
Subject: [IR] Fix mayReadFromMemory() for writeonly calls
X-Git-Tag: llvmorg-11-init~6064
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=5e5af533ab16bad6dc5519b97b1820732d0141a5;p=platform%2Fupstream%2Fllvm.git

[IR] Fix mayReadFromMemory() for writeonly calls

Current implementation of Instruction::mayReadFromMemory()
returns !doesNotAccessMemory() which is !ReadNone. This
does not take into account that the writeonly attribute
also indicates that the call does not read from memory.

The patch changes the predicate to !doesNotReadMemory()
that reflects the intended behavior.

Differential Revision: https://reviews.llvm.org/D69086

llvm-svn: 375389
---

diff --git a/llvm/lib/IR/Instruction.cpp b/llvm/lib/IR/Instruction.cpp
index ba5629d..b157c7b 100644
--- a/llvm/lib/IR/Instruction.cpp
+++ b/llvm/lib/IR/Instruction.cpp
@@ -524,7 +524,7 @@ bool Instruction::mayReadFromMemory() const {
   case Instruction::Call:
   case Instruction::Invoke:
   case Instruction::CallBr:
-    return !cast<CallBase>(this)->doesNotAccessMemory();
+    return !cast<CallBase>(this)->doesNotReadMemory();
   case Instruction::Store:
     return !cast<StoreInst>(this)->isUnordered();
   }
diff --git a/llvm/test/CodeGen/AMDGPU/llvm.amdgcn.ds.gws.init.ll b/llvm/test/CodeGen/AMDGPU/llvm.amdgcn.ds.gws.init.ll
index a7a8fa7..9c39593 100644
--- a/llvm/test/CodeGen/AMDGPU/llvm.amdgcn.ds.gws.init.ll
+++ b/llvm/test/CodeGen/AMDGPU/llvm.amdgcn.ds.gws.init.ll
@@ -114,7 +114,7 @@ define amdgpu_kernel void @gws_init_vgpr_offset_add(i32 %val) #0 {
 ; LOOP: s_mov_b32 m0, -1
 ; LOOP: ds_write_b32
 define amdgpu_kernel void @gws_init_save_m0_init_constant_offset(i32 %val) #0 {
-  store i32 1, i32 addrspace(3)* @lds
+  store volatile i32 1, i32 addrspace(3)* @lds
   call void @llvm.amdgcn.ds.gws.init(i32 %val, i32 10)
   store i32 2, i32 addrspace(3)* @lds
   ret void
diff --git a/llvm/test/Transforms/EarlyCSE/writeonly.ll b/llvm/test/Transforms/EarlyCSE/writeonly.ll
new file mode 100644
index 0000000..0a3cd1c
--- /dev/null
+++ b/llvm/test/Transforms/EarlyCSE/writeonly.ll
@@ -0,0 +1,15 @@
+; RUN: opt -S -early-cse < %s | FileCheck %s
+
+@var = global i32 undef
+declare void @foo() nounwind
+
+define void @test() {
+; CHECK-LABEL: @test(
+; CHECK-NOT: store
+  store i32 1, i32* @var
+; CHECK: call void @foo()
+  call void @foo() writeonly
+; CHECK: store i32 2, i32* @var
+  store i32 2, i32* @var
+  ret void
+}