Fix icmp lowering

Summary:
During icmp lowering it can happen that a constant value can be larger than expected (see the code around the change).
APInt::getMinSignedBits() must be checked again as the shift before can change the constant sign to positive.
I'm not sure it is the best fix possible though.

Test Plan: Regression test included.

Reviewers: resistor, chandlerc, spatel, hfinkel

Reviewed By: hfinkel

Subscribers: hfinkel, llvm-commits

Differential Revision: http://reviews.llvm.org/D9147

llvm-svn: 237812

1 files changed, 50 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/Generic/icmp-illegal.ll b/llvm/test/CodeGen/Generic/icmp-illegal.ll
new file mode 100644
index 00000000000..23d20c04652
--- /dev/null
+++ b/llvm/test/CodeGen/Generic/icmp-illegal.ll
@@ -0,0 +1,50 @@
+
+; RUN: llc < %s | FileCheck %s
+
+; CHECK-LABEL: test_ult
+define i1 @test_ult(i256 %a) nounwind {
+  %1 = icmp ult i256 %a, -6432394258550908438
+  ret i1 %1
+}
+
+; CHECK-LABEL: test_ule
+define i1 @test_ule(i256 %a) nounwind {
+  %1 = icmp ule i256 %a, -6432394258550908438
+  ret i1 %1
+}
+
+; CHECK-LABEL: test_ugt
+define i1 @test_ugt(i256 %a) nounwind {
+  %1 = icmp ugt i256 %a, -6432394258550908438
+  ret i1 %1
+}
+
+; CHECK-LABEL: test_uge
+define i1 @test_uge(i256 %a) nounwind {
+  %1 = icmp uge i256 %a, -6432394258550908438
+  ret i1 %1
+}
+
+; CHECK-LABEL: test_slt
+define i1 @test_slt(i256 %a) nounwind {
+  %1 = icmp slt i256 %a, -6432394258550908438
+  ret i1 %1
+}
+
+; CHECK-LABEL: test_sle
+define i1 @test_sle(i256 %a) nounwind {
+  %1 = icmp sle i256 %a, -6432394258550908438
+  ret i1 %1
+}
+
+; CHECK-LABEL: test_sgt
+define i1 @test_sgt(i256 %a) nounwind {
+  %1 = icmp sgt i256 %a, -6432394258550908438
+  ret i1 %1
+}
+
+; CHECK-LABEL: test_sge
+define i1 @test_sge(i256 %a) nounwind {
+  %1 = icmp sge i256 %a, -6432394258550908438
+  ret i1 %1
+}