[NewGVN] Fix handling of assumes

This patch fixes two bugs:

* test1: Previously assume(a >= 5) concluded that a == 5. That's only
         valid for assume(a == 5)...
* test2: If operands were swapped, additional users were added to the
         wrong cmp operand. This resulted in an "unsettled iteration"
         assertion failure.

Patch by Nikita Popov

Differential Revision: https://reviews.llvm.org/D46974

llvm-svn: 333007

1 files changed, 26 insertions, 0 deletions

diff --git a/llvm/test/Transforms/NewGVN/assumes.ll b/llvm/test/Transforms/NewGVN/assumes.ll
new file mode 100644
index 00000000000..065cc0fb62e
--- /dev/null
+++ b/llvm/test/Transforms/NewGVN/assumes.ll
@@ -0,0 +1,26 @@
+; RUN: opt < %s -newgvn -S | FileCheck %s
+
+; CHECK-LABEL: @test1
+; CHECK: ret i32 %arg
+define i32 @test1(i32 %arg) {
+  %cmp = icmp sge i32 %arg, 5
+  call void @llvm.assume(i1 %cmp)
+  ret i32 %arg
+}
+
+; CHECK-LABEL: @test2
+; CHECK: ret i32 %arg
+define i32 @test2(i32 %arg, i1 %b) {
+  br label %bb
+
+bb:
+  %a = phi i32 [ 1, %0 ], [ 2, %bb ]
+  %cmp = icmp eq i32 %arg, %a
+  call void @llvm.assume(i1 %cmp)
+  br i1 %b, label %bb, label %end
+
+end:
+  ret i32 %arg
+}
+
+declare void @llvm.assume(i1 %cond)