1 files changed, 146 insertions, 0 deletions
diff --git a/llvm/test/Transforms/GVN/PRE/pre-load-guards.ll b/llvm/test/Transforms/GVN/PRE/pre-load-guards.ll
new file mode 100644
index 00000000000..eeb3ef649d9
--- /dev/null
+++ b/llvm/test/Transforms/GVN/PRE/pre-load-guards.ll
@@ -0,0 +1,146 @@
+; RUN: opt < %s -basicaa -gvn -enable-load-pre -S | FileCheck %s
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+
+declare void @llvm.experimental.guard(i1, ...)
+
+; This is a motivating example on why we prohibit hoisting through guards.
+; In the bottom block, we check that the index is within bounds and only access
+; the element in this case and deoptimize otherwise. If we hoist the load to a
+; place above the guard, it will may lead to out-of-bound array access.
+define i32 @test_motivation(i32* %p, i32* %q, i1 %C, i32 %index, i32 %len) {
+; CHECK-LABEL: @test_motivation(
+block1:
+  %el1 = getelementptr inbounds i32, i32* %q, i32 %index
+  %el2 = getelementptr inbounds i32, i32* %p, i32 %index
+	br i1 %C, label %block2, label %block3
+
+block2:
+
+; CHECK:        block2:
+; CHECK-NEXT:     br
+; CHECK-NOT:      load
+; CHECK-NOT:      sge
+; CHECK-NOT:      slt
+; CHECK-NOT:      and
+  br label %block4
+
+block3:
+  store i32 0, i32* %el1
+  br label %block4
+
+block4:
+
+; CHECK:        block4:
+; CHECK:          %cond1 = icmp sge i32 %index, 0
+; CHECK-NEXT:     %cond2 = icmp slt i32 %index, %len
+; CHECK-NEXT:     %in.bounds = and i1 %cond1, %cond2
+; CHECK:          call void (i1, ...) @llvm.experimental.guard(i1 %in.bounds)
+; CHECK-NEXT:     %PRE = load i32, i32* %P2
+; CHECK:          ret i32 %PRE
+
+  %P2 = phi i32* [%el2, %block3], [%el1, %block2]
+  %cond1 = icmp sge i32 %index, 0
+  %cond2 = icmp slt i32 %index, %len
+  %in.bounds = and i1 %cond1, %cond2
+  call void (i1, ...) @llvm.experimental.guard(i1 %in.bounds) [ "deopt"() ]
+  %PRE = load i32, i32* %P2
+  ret i32 %PRE
+}
+
+; Guard in load's block that is above the load should prohibit the PRE.
+define i32 @test_guard_01(i32* %p, i32* %q, i1 %C, i1 %G) {
+; CHECK-LABEL: @test_guard_01(
+block1:
+	br i1 %C, label %block2, label %block3
+
+block2:
+
+; CHECK:        block2:
+; CHECK-NEXT:     br
+; CHECK-NOT:      load
+
+ br label %block4
+
+block3:
+  store i32 0, i32* %p
+  br label %block4
+
+block4:
+
+; CHECK:        block4:
+; CHECK:          call void (i1, ...) @llvm.experimental.guard(i1 %G)
+; CHECK-NEXT:     load
+; CHECK:          ret i32
+
+  %P2 = phi i32* [%p, %block3], [%q, %block2]
+  call void (i1, ...) @llvm.experimental.guard(i1 %G) [ "deopt"() ]
+  %PRE = load i32, i32* %P2
+  ret i32 %PRE
+}
+
+; Guard in load's block that is below the load should not prohibit the PRE.
+define i32 @test_guard_02(i32* %p, i32* %q, i1 %C, i1 %G) {
+; CHECK-LABEL: @test_guard_02(
+block1:
+	br i1 %C, label %block2, label %block3
+
+block2:
+
+; CHECK:        block2:
+; CHECK-NEXT:     load i32, i32* %q
+
+ br label %block4
+
+block3:
+  store i32 0, i32* %p
+  br label %block4
+
+block4:
+
+; CHECK:        block4:
+; CHECK-NEXT:     phi i32 [
+; CHECK-NEXT:     phi i32* [
+; CHECK-NEXT:     call void (i1, ...) @llvm.experimental.guard(i1 %G)
+; CHECK-NOT:      load
+; CHECK:          ret i32
+
+  %P2 = phi i32* [%p, %block3], [%q, %block2]
+  %PRE = load i32, i32* %P2
+  call void (i1, ...) @llvm.experimental.guard(i1 %G) [ "deopt"() ]
+  ret i32 %PRE
+}
+
+; Guard above the load's block should prevent PRE from hoisting through it.
+define i32 @test_guard_03(i32* %p, i32* %q, i1 %C, i1 %G) {
+; CHECK-LABEL: @test_guard_03(
+block1:
+	br i1 %C, label %block2, label %block3
+
+block2:
+
+; CHECK:        block2:
+; CHECK-NEXT:     br
+; CHECK-NOT:      load
+
+ br label %block4
+
+block3:
+  store i32 0, i32* %p
+  br label %block4
+
+block4:
+
+; CHECK:        block4:
+; CHECK-NEXT:     phi i32*
+; CHECK-NEXT:     call void (i1, ...) @llvm.experimental.guard(i1 %G)
+; CHECK-NEXT:     load
+; CHECK-NEXT:     ret i32
+
+  %P2 = phi i32* [%p, %block3], [%q, %block2]
+  call void (i1, ...) @llvm.experimental.guard(i1 %G) [ "deopt"() ]
+  br label %block5
+
+block5:
+  %PRE = load i32, i32* %P2
+  ret i32 %PRE
+}