Add 'umax' similar to 'smax' SCEV. Closes PR2003.

Parse reversed smax and umax as smin and umin and express them with negative
or binary-not SCEVs (which are really just subtract under the hood).

Parse 'xor %x, -1' as (-1 - %x).

Remove dead code (ConstantInt::get always returns a ConstantInt).

Don't use getIntegerSCEV(-1, Ty). The first value is an int, then it gets
passed into a uint64_t. Instead, create the -1 directly from
ConstantInt::getAllOnesValue().

llvm-svn: 47360

2 files changed, 18 insertions, 1 deletions

diff --git a/llvm/test/Analysis/ScalarEvolution/2007-08-06-Unsigned.ll b/llvm/test/Analysis/ScalarEvolution/2007-08-06-Unsigned.ll
index e725852cea1..23ffc650b0d 100644
--- a/llvm/test/Analysis/ScalarEvolution/2007-08-06-Unsigned.ll
+++ b/llvm/test/Analysis/ScalarEvolution/2007-08-06-Unsigned.ll
@@ -1,4 +1,4 @@
-; RUN: llvm-as < %s | opt -scalar-evolution -analyze | grep {Loop bb: ( -1 + ( -1 \\*  %x) +  %y) iterations!}
+; RUN: llvm-as < %s | opt -scalar-evolution -analyze | grep {Loop bb: ( -1 + ( -1 \\*  %x) + (( 1 +  %x) umax  %y)) iterations!}
 ; PR1597
 
 define i32 @f(i32 %x, i32 %y) {
diff --git a/llvm/test/Analysis/ScalarEvolution/2008-02-15-UMax.ll b/llvm/test/Analysis/ScalarEvolution/2008-02-15-UMax.ll
new file mode 100644
index 00000000000..0f977f804eb
--- /dev/null
+++ b/llvm/test/Analysis/ScalarEvolution/2008-02-15-UMax.ll
@@ -0,0 +1,17 @@
+; RUN: llvm-as < %s | opt -analyze -scalar-evolution | grep umax
+; PR2003
+
+define i32 @foo(i32 %n) {
+entry:
+        br label %header
+header:
+        %i = phi i32 [ 100, %entry ], [ %i.inc, %next ]
+        %cond = icmp ult i32 %i, %n
+        br i1 %cond, label %next, label %return
+next:
+        %i.inc = add i32 %i, 1
+        br label %header
+return:
+        ret i32 %i
+}
+