Don't merge two constants if we care about the address of both.

This fixes the original testcase in PR8927. It also causes a clang
binary built with a patched clang to increase in size by 0.21%.

We can probably get some of the size back by writing a pass that
detects that a global never has its pointer compared and adds
unnamed_addr to it (maybe extend global opt). It is also possible that
there are some other cases clang could add unnamed_addr to.

I will investigate extending globalopt next.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@123584 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 67 insertions, 1 deletions

diff --git a/test/Transforms/ConstantMerge/2011-01-15-EitherOrder.ll b/test/Transforms/ConstantMerge/2011-01-15-EitherOrder.ll
index 7001ce1..f561daf 100644
--- a/test/Transforms/ConstantMerge/2011-01-15-EitherOrder.ll
+++ b/test/Transforms/ConstantMerge/2011-01-15-EitherOrder.ll
@@ -5,7 +5,7 @@ declare i32 @zed(%struct.foobar*, %struct.foobar*)
 
 %struct.foobar = type { i32 }
 ; CHECK: bar.d
-@bar.d =  constant %struct.foobar zeroinitializer, align 4
+@bar.d =  unnamed_addr constant %struct.foobar zeroinitializer, align 4
 ; CHECK-NOT: foo.d
 @foo.d = internal constant %struct.foobar zeroinitializer, align 4
 define i32 @main() nounwind ssp {
diff --git a/test/Transforms/ConstantMerge/merge-both.ll b/test/Transforms/ConstantMerge/merge-both.ll
new file mode 100644
index 0000000..0282f46
--- /dev/null
+++ b/test/Transforms/ConstantMerge/merge-both.ll
@@ -0,0 +1,26 @@
+; RUN: opt -constmerge %s -S -o - | FileCheck %s
+; Test that in one run var3 is merged into var2 and var1 into var4.
+
+declare void @zed(%struct.foobar*, %struct.foobar*)
+
+%struct.foobar = type { i32 }
+
+@var1 = internal constant %struct.foobar { i32 2 }
+@var2 = unnamed_addr constant %struct.foobar { i32 2 }
+@var3 = internal constant %struct.foobar { i32 2 }
+@var4 = unnamed_addr constant %struct.foobar { i32 2 }
+
+; CHECK:      %struct.foobar = type { i32 }
+; CHECK-NOT: @
+; CHECK: @var2 = constant %struct.foobar { i32 2 }
+; CHECK-NEXT: @var4 = constant %struct.foobar { i32 2 }
+; CHECK-NOT: @
+; CHECK: declare void @zed(%struct.foobar*, %struct.foobar*)
+
+define i32 @main() {
+entry:
+  call void @zed(%struct.foobar* @var1, %struct.foobar* @var2)
+  call void @zed(%struct.foobar* @var3, %struct.foobar* @var4)
+  ret i32 0
+}
+
diff --git a/test/Transforms/ConstantMerge/unnamed-addr.ll b/test/Transforms/ConstantMerge/unnamed-addr.ll
new file mode 100644
index 0000000..2410083
--- /dev/null
+++ b/test/Transforms/ConstantMerge/unnamed-addr.ll
@@ -0,0 +1,40 @@
+; RUN: opt -constmerge %s -S -o - | FileCheck %s
+; Test which corresponding x and y are merged and that unnamed_addr
+; is correctly set.
+
+declare void @zed(%struct.foobar*, %struct.foobar*)
+
+%struct.foobar = type { i32 }
+
+@test1.x = internal constant %struct.foobar { i32 1 }
+@test1.y = constant %struct.foobar { i32 1 }
+
+@test2.x = internal constant %struct.foobar { i32 2 }
+@test2.y = unnamed_addr constant %struct.foobar { i32 2 }
+
+@test3.x = internal unnamed_addr constant %struct.foobar { i32 3 }
+@test3.y = constant %struct.foobar { i32 3 }
+
+@test4.x = internal unnamed_addr constant %struct.foobar { i32 4 }
+@test4.y = unnamed_addr constant %struct.foobar { i32 4 }
+
+
+; CHECK:      %struct.foobar = type { i32 }
+; CHECK-NOT: @
+; CHECK: @test1.x = internal constant %struct.foobar { i32 1 }
+; CHECK-NEXT: @test1.y = constant %struct.foobar { i32 1 }
+; CHECK-NEXT: @test2.y = constant %struct.foobar { i32 2 }
+; CHECK-NEXT: @test3.y = constant %struct.foobar { i32 3 }
+; CHECK-NEXT: @test4.y = unnamed_addr constant %struct.foobar { i32 4 }
+; CHECK-NOT: @
+; CHECK: declare void @zed(%struct.foobar*, %struct.foobar*)
+
+define i32 @main() {
+entry:
+  call void @zed(%struct.foobar* @test1.x, %struct.foobar* @test1.y)
+  call void @zed(%struct.foobar* @test2.x, %struct.foobar* @test2.y)
+  call void @zed(%struct.foobar* @test3.x, %struct.foobar* @test3.y)
+  call void @zed(%struct.foobar* @test4.x, %struct.foobar* @test4.y)
+  ret i32 0
+}
+