R600/SI: Only select SALU instructions in the entry or exit block

SALU instructions ignore control flow, so it is not always safe to use
them within branches.  This is a partial solution to this problem
until we can come up with something better.

llvm-svn: 207590

1 files changed, 27 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/R600/sgpr-control-flow.ll b/llvm/test/CodeGen/R600/sgpr-control-flow.ll
new file mode 100644
index 00000000000..06ad24d959c
--- /dev/null
+++ b/llvm/test/CodeGen/R600/sgpr-control-flow.ll
@@ -0,0 +1,27 @@
+; RUN: llc -march=r600 -mcpu=SI -verify-machineinstrs< %s | FileCheck -check-prefix=SI %s
+;
+;
+; Most SALU instructions ignore control flow, so we need to make sure
+; they don't overwrite values from other blocks.
+
+; SI-NOT: S_ADD
+
+define void @sgpr_if_else(i32 addrspace(1)* %out, i32 %a, i32 %b, i32 %c, i32 %d, i32 %e) {
+entry:
+  %0 = icmp eq i32 %a, 0
+  br i1 %0, label %if, label %else
+
+if:
+  %1 = add i32 %b, %c
+  br label %endif
+
+else:
+  %2 = add i32 %d, %e
+  br label %endif
+
+endif:
+  %3 = phi i32 [%1, %if], [%2, %else]
+  %4 = add i32 %3, %a
+  store i32 %4, i32 addrspace(1)* %out
+  ret void
+}