From 9dc6eddb1d104b18af1bf06c6f8ee202a12b5014 Mon Sep 17 00:00:00 2001
From: Daniel Berlin <dberlin@dberlin.org>
Date: Thu, 24 Aug 2017 02:43:17 +0000
Subject: [PATCH] NewGVN: We weren't properly simplifying selects with equal
 arguments due to a thinko.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311626 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Transforms/Scalar/NewGVN.cpp |  2 +-
 test/Transforms/NewGVN/basic.ll  | 34 ++++++++++++++++++++++++--------
 2 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/lib/Transforms/Scalar/NewGVN.cpp b/lib/Transforms/Scalar/NewGVN.cpp
index e545163c96c..475ee67f531 100644
--- a/lib/Transforms/Scalar/NewGVN.cpp
+++ b/lib/Transforms/Scalar/NewGVN.cpp
@@ -1025,7 +1025,7 @@ const Expression *NewGVN::createExpression(Instruction *I) const {
       return SimplifiedE;
   } else if (isa<SelectInst>(I)) {
     if (isa<Constant>(E->getOperand(0)) ||
-        E->getOperand(0) == E->getOperand(1)) {
+        E->getOperand(1) == E->getOperand(2)) {
       assert(E->getOperand(1)->getType() == I->getOperand(1)->getType() &&
              E->getOperand(2)->getType() == I->getOperand(2)->getType());
       Value *V = SimplifySelectInst(E->getOperand(0), E->getOperand(1),
diff --git a/test/Transforms/NewGVN/basic.ll b/test/Transforms/NewGVN/basic.ll
index 587e9abe033..90193bdbcda 100644
--- a/test/Transforms/NewGVN/basic.ll
+++ b/test/Transforms/NewGVN/basic.ll
@@ -1,17 +1,35 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
 ; RUN: opt < %s -newgvn -S | FileCheck %s
 
 define i32 @main() {
+; CHECK-LABEL: @main(
+; CHECK-NEXT:  block1:
+; CHECK-NEXT:    br label [[BLOCK2:%.*]]
+; CHECK:       block2:
+; CHECK-NEXT:    ret i32 0
+;
 block1:
-	%z1 = bitcast i32 0 to i32
-	br label %block2
+  %z1 = bitcast i32 0 to i32
+  br label %block2
 block2:
   %z2 = bitcast i32 0 to i32
   ret i32 %z2
 }
 
-; CHECK: define i32 @main() {
-; CHECK-NEXT: block1:
-; CHECK-NEXT:   br label %block2
-; CHECK: block2:
-; CHECK-NEXT:   ret i32 0
-; CHECK-NEXT: }
+; Test that we simplify selects properly
+define i64 @simplifyselect(i64 %x, i64 %y, i1 %c1, i1 %c2, i1 %zzz) {
+; CHECK-LABEL: @simplifyselect(
+; CHECK-NEXT:    [[SHARED:%.*]] = add i64 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT:    [[R1:%.*]] = select i1 [[C1:%.*]], i64 [[SHARED]], i64 [[X]]
+; CHECK-NEXT:    [[R2:%.*]] = select i1 [[C2:%.*]], i64 [[SHARED]], i64 [[Y]]
+; CHECK-NEXT:    [[R:%.*]] = add i64 [[R1]], [[R2]]
+; CHECK-NEXT:    ret i64 [[R]]
+;
+  %shared = add i64 %x, %y
+  %r1 = select i1 %c1, i64 %shared, i64 %x
+  %r2 = select i1 %c2, i64 %shared, i64 %y
+  %tmp = select i1 %c2, i64 %x, i64 0
+  %r2_eq2 = select i1 %zzz, i64 %r2, i64 %r2
+  %r = add i64 %r1, %r2_eq2
+  ret i64 %r
+}
-- 
2.50.1