Reland r216439 215441, majnemer has a real fix for PR20771.

llvm-svn: 216586

1 files changed, 66 insertions, 0 deletions

diff --git a/llvm/test/Transforms/InstSimplify/gep.ll b/llvm/test/Transforms/InstSimplify/gep.ll
new file mode 100644
index 00000000000..d1704bf80bc
--- /dev/null
+++ b/llvm/test/Transforms/InstSimplify/gep.ll
@@ -0,0 +1,66 @@
+; RUN: opt -S -instsimplify < %s | FileCheck %s
+
+target datalayout = "e-m:o-i64:64-f80:128-n8:16:32:64-S128"
+
+%struct.A = type { [7 x i8] }
+
+define %struct.A* @test1(%struct.A* %b, %struct.A* %e) {
+  %e_ptr = ptrtoint %struct.A* %e to i64
+  %b_ptr = ptrtoint %struct.A* %b to i64
+  %sub = sub i64 %e_ptr, %b_ptr
+  %sdiv = sdiv exact i64 %sub, 7
+  %gep = getelementptr inbounds %struct.A* %b, i64 %sdiv
+  ret %struct.A* %gep
+; CHECK-LABEL: @test1
+; CHECK-NEXT: ret %struct.A* %e
+}
+
+define i8* @test2(i8* %b, i8* %e) {
+  %e_ptr = ptrtoint i8* %e to i64
+  %b_ptr = ptrtoint i8* %b to i64
+  %sub = sub i64 %e_ptr, %b_ptr
+  %gep = getelementptr inbounds i8* %b, i64 %sub
+  ret i8* %gep
+; CHECK-LABEL: @test2
+; CHECK-NEXT: ret i8* %e
+}
+
+define i64* @test3(i64* %b, i64* %e) {
+  %e_ptr = ptrtoint i64* %e to i64
+  %b_ptr = ptrtoint i64* %b to i64
+  %sub = sub i64 %e_ptr, %b_ptr
+  %ashr = ashr exact i64 %sub, 3
+  %gep = getelementptr inbounds i64* %b, i64 %ashr
+  ret i64* %gep
+; CHECK-LABEL: @test3
+; CHECK-NEXT: ret i64* %e
+}
+
+define %struct.A* @test4(%struct.A* %b) {
+  %b_ptr = ptrtoint %struct.A* %b to i64
+  %sub = sub i64 0, %b_ptr
+  %sdiv = sdiv exact i64 %sub, 7
+  %gep = getelementptr inbounds %struct.A* %b, i64 %sdiv
+  ret %struct.A* %gep
+; CHECK-LABEL: @test4
+; CHECK-NEXT: ret %struct.A* null
+}
+
+define i8* @test5(i8* %b) {
+  %b_ptr = ptrtoint i8* %b to i64
+  %sub = sub i64 0, %b_ptr
+  %gep = getelementptr inbounds i8* %b, i64 %sub
+  ret i8* %gep
+; CHECK-LABEL: @test5
+; CHECK-NEXT: ret i8* null
+}
+
+define i64* @test6(i64* %b) {
+  %b_ptr = ptrtoint i64* %b to i64
+  %sub = sub i64 0, %b_ptr
+  %ashr = ashr exact i64 %sub, 3
+  %gep = getelementptr inbounds i64* %b, i64 %ashr
+  ret i64* %gep
+; CHECK-LABEL: @test6
+; CHECK-NEXT: ret i64* null
+}