[SystemZ] Check for legality before doing LOAD AND TEST transformations.

Since a load and test instruction treat its operands as signed, it can only
replace a logical compare for EQ/NE uses.

Review: Ulrich Weigand
https://bugs.llvm.org/show_bug.cgi?id=35662

llvm-svn: 322488

1 files changed, 52 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/SystemZ/load-and-test.mir b/llvm/test/CodeGen/SystemZ/load-and-test.mir
new file mode 100644
index 00000000000..da01dbc79a9
--- /dev/null
+++ b/llvm/test/CodeGen/SystemZ/load-and-test.mir
@@ -0,0 +1,52 @@
+# RUN: llc -mtriple=s390x-linux-gnu -mcpu=z13 -start-before=postrapseudos %s -o - \
+# RUN:   | FileCheck %s
+#
+# Check that integer load and test instructions are not emitted for unsigned
+# comparisons unless checking for equality. That would be wrong, since the
+# operands are implicitly treated as signed values.
+
+# Not legal: Logical comparison used for >= (CCMask is 10).
+# CHECK-LABEL: fun0
+# CHECK-NOT: lt
+---
+name:            fun0
+tracksRegLiveness: true
+body:             |
+  bb.0 ():
+    liveins: %r1d
+    renamable %r0l = L %r1d, 0, %noreg
+    CLFIMux killed renamable %r0l, 0, implicit-def %cc
+    BRC 14, 10, %bb.2, implicit %cc
+
+  bb.1 ():
+    liveins: %r0l
+    ST killed renamable %r0l, %r15d, 164, %noreg
+
+  bb.2 ():
+    liveins: %r0l
+    ST killed renamable %r0l, %r15d, 164, %noreg
+    Return
+...
+
+# Legal: Logical comparison used for == (CCMask is 8).
+# CHECK-LABEL: fun1
+# CHECK: lt
+---
+name:            fun1
+tracksRegLiveness: true
+body:             |
+  bb.0 ():
+    liveins: %r1d
+    renamable %r0l = L %r1d, 0, %noreg
+    CLFIMux killed renamable %r0l, 0, implicit-def %cc
+    BRC 14, 8, %bb.2, implicit %cc
+
+  bb.1 ():
+    liveins: %r0l
+    ST killed renamable %r0l, %r15d, 164, %noreg
+
+  bb.2 ():
+    liveins: %r0l
+    ST killed renamable %r0l, %r15d, 164, %noreg
+    Return
+...