From 12f6308247582b36ad8ddf0cdba9b9a7829620e7 Mon Sep 17 00:00:00 2001
From: Pawel Bylica <chfast@gmail.com>
Date: Wed, 20 May 2015 17:21:09 +0000
Subject: [PATCH] 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

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237812 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SelectionDAG/TargetLowering.cpp |  3 +-
 test/CodeGen/Generic/icmp-illegal.ll        | 50 +++++++++++++++++++++
 2 files changed, 52 insertions(+), 1 deletion(-)
 create mode 100644 test/CodeGen/Generic/icmp-illegal.ll

diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 38e39e52e81..055406ce751 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1730,7 +1730,8 @@ TargetLowering::SimplifySetCC(EVT VT, SDValue N0, SDValue N1,
           ShiftBits = C1.countTrailingZeros();
         }
         NewC = NewC.lshr(ShiftBits);
-        if (ShiftBits && isLegalICmpImmediate(NewC.getSExtValue())) {
+        if (ShiftBits && NewC.getMinSignedBits() <= 64 &&
+          isLegalICmpImmediate(NewC.getSExtValue())) {
           EVT ShiftTy = DCI.isBeforeLegalize() ?
             getPointerTy() : getShiftAmountTy(N0.getValueType());
           EVT CmpTy = N0.getValueType();
diff --git a/test/CodeGen/Generic/icmp-illegal.ll b/test/CodeGen/Generic/icmp-illegal.ll
new file mode 100644
index 00000000000..23d20c04652
--- /dev/null
+++ b/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
+}
-- 
2.34.1