From e018b8bbb0ba8ac1bb36931827c2fbc3ec31c1da Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo@fhahn.com>
Date: Wed, 29 Apr 2020 10:30:05 +0100
Subject: [PATCH] [DSE,MSSA] Add multi-path tests with readnone throwing calls.

---
 .../MSSA/multiblock-multipath-throwing.ll     | 171 ++++++++++++++++++
 1 file changed, 171 insertions(+)
 create mode 100644 llvm/test/Transforms/DeadStoreElimination/MSSA/multiblock-multipath-throwing.ll

diff --git a/llvm/test/Transforms/DeadStoreElimination/MSSA/multiblock-multipath-throwing.ll b/llvm/test/Transforms/DeadStoreElimination/MSSA/multiblock-multipath-throwing.ll
new file mode 100644
index 000000000000..b9bdcfe324f9
--- /dev/null
+++ b/llvm/test/Transforms/DeadStoreElimination/MSSA/multiblock-multipath-throwing.ll
@@ -0,0 +1,171 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -basicaa -dse -enable-dse-memoryssa -S | FileCheck %s
+
+target datalayout = "e-m:e-p:32:32-i64:64-v128:64:128-a:0:32-n32-S64"
+
+declare void @readnone_may_throw() readnone
+
+declare void @use(i32 *)
+
+; Tests where the pointer/object is accessible after the function returns.
+
+; Cannot remove the store from the entry block, because the call in bb2 may throw.
+define void @accessible_after_return_1(i32* noalias %P, i1 %c1) {
+; CHECK-LABEL: @accessible_after_return_1(
+; CHECK-NEXT:    store i32 1, i32* [[P:%.*]]
+; CHECK-NEXT:    br i1 [[C1:%.*]], label [[BB1:%.*]], label [[BB2:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    store i32 0, i32* [[P]]
+; CHECK-NEXT:    br label [[BB5:%.*]]
+; CHECK:       bb2:
+; CHECK-NEXT:    call void @readnone_may_throw()
+; CHECK-NEXT:    store i32 3, i32* [[P]]
+; CHECK-NEXT:    br label [[BB5]]
+; CHECK:       bb5:
+; CHECK-NEXT:    call void @use(i32* [[P]])
+; CHECK-NEXT:    ret void
+;
+  store i32 1, i32* %P
+  br i1 %c1, label %bb1, label %bb2
+
+bb1:
+  store i32 0, i32* %P
+  br label %bb5
+
+bb2:
+  call void @readnone_may_throw()
+  store i32 3, i32* %P
+  br label %bb5
+
+bb5:
+  call void @use(i32* %P)
+  ret void
+}
+
+; Cannot remove the store from the entry block, because the call in bb3 may throw.
+define void @accessible_after_return6(i32* %P, i1 %c.1, i1 %c.2) {
+; CHECK-LABEL: @accessible_after_return6(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    store i32 0, i32* [[P:%.*]]
+; CHECK-NEXT:    br i1 [[C_1:%.*]], label [[BB1:%.*]], label [[BB2:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    br i1 [[C_2:%.*]], label [[BB3:%.*]], label [[BB4:%.*]]
+; CHECK:       bb2:
+; CHECK-NEXT:    store i32 1, i32* [[P]]
+; CHECK-NEXT:    ret void
+; CHECK:       bb3:
+; CHECK-NEXT:    call void @readnone_may_throw()
+; CHECK-NEXT:    store i32 2, i32* [[P]]
+; CHECK-NEXT:    ret void
+; CHECK:       bb4:
+; CHECK-NEXT:    store i32 3, i32* [[P]]
+; CHECK-NEXT:    ret void
+;
+entry:
+  store i32 0, i32* %P
+  br i1 %c.1, label %bb1, label %bb2
+
+bb1:
+  br i1 %c.2, label %bb3, label %bb4
+
+bb2:
+  store i32 1, i32* %P
+  ret void
+
+bb3:
+  call void @readnone_may_throw()
+  store i32 2, i32* %P
+  ret void
+
+bb4:
+  store i32 3, i32* %P
+  ret void
+}
+
+; Tests where the pointer/object is *NOT* accessible after the function returns.
+
+; The store in the entry block can be eliminated, because it is overwritten
+; on all paths to the exit. As the location is not visible to the caller, the
+; call in bb2 (which may throw) can be ignored.
+define void @alloca_1(i1 %c1) {
+; CHECK-LABEL: @alloca_1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[P:%.*]] = alloca i32
+; CHECK-NEXT:    br i1 [[C1:%.*]], label [[BB1:%.*]], label [[BB2:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    store i32 0, i32* [[P]]
+; CHECK-NEXT:    br label [[BB5:%.*]]
+; CHECK:       bb2:
+; CHECK-NEXT:    call void @readnone_may_throw()
+; CHECK-NEXT:    store i32 3, i32* [[P]]
+; CHECK-NEXT:    br label [[BB5]]
+; CHECK:       bb5:
+; CHECK-NEXT:    call void @use(i32* [[P]])
+; CHECK-NEXT:    ret void
+;
+entry:
+  %P = alloca i32
+  store i32 1, i32* %P
+  br i1 %c1, label %bb1, label %bb2
+
+bb1:
+  store i32 0, i32* %P
+  br label %bb5
+
+bb2:
+  call void @readnone_may_throw()
+  store i32 3, i32* %P
+  br label %bb5
+
+bb5:
+  call void @use(i32* %P)
+  ret void
+}
+
+; The store in the entry block can be eliminated, because it is overwritten
+; on all paths to the exit. As the location is not visible to the caller, the
+; call in bb3 (which may throw) can be ignored.
+define void @alloca_2(i1 %c.1, i1 %c.2) {
+; CHECK-LABEL: @alloca_2(
+; CHECK-NEXT:    [[P:%.*]] = alloca i32
+; CHECK-NEXT:    br i1 [[C_1:%.*]], label [[BB1:%.*]], label [[BB2:%.*]]
+; CHECK:       bb1:
+; CHECK-NEXT:    store i32 0, i32* [[P]]
+; CHECK-NEXT:    br label [[BB5:%.*]]
+; CHECK:       bb2:
+; CHECK-NEXT:    br i1 [[C_2:%.*]], label [[BB3:%.*]], label [[BB4:%.*]]
+; CHECK:       bb3:
+; CHECK-NEXT:    call void @readnone_may_throw()
+; CHECK-NEXT:    store i32 3, i32* [[P]]
+; CHECK-NEXT:    br label [[BB5]]
+; CHECK:       bb4:
+; CHECK-NEXT:    store i32 5, i32* [[P]]
+; CHECK-NEXT:    br label [[BB5]]
+; CHECK:       bb5:
+; CHECK-NEXT:    call void @use(i32* [[P]])
+; CHECK-NEXT:    ret void
+;
+  %P = alloca i32
+  store i32 1, i32* %P
+  br i1 %c.1, label %bb1, label %bb2
+
+bb1:
+  store i32 0, i32* %P
+  br label %bb5
+
+bb2:
+  br i1 %c.2, label %bb3, label %bb4
+
+bb3:
+  call void @readnone_may_throw()
+  store i32 3, i32* %P
+  br label %bb5
+
+bb4:
+  store i32 5, i32* %P
+  br label %bb5
+
+bb5:
+  call void @use(i32* %P)
+  ret void
+}