[Hexagon] Implement RDF-based post-RA optimizations

- Handle simple cases of register copies (what current RDF CP allows).
- Hexagon-specific dead code elimination: handles dead address updates
  in post-increment instructions.

llvm-svn: 257504

1 files changed, 31 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/Hexagon/rdf-dead-loop.ll b/llvm/test/CodeGen/Hexagon/rdf-dead-loop.ll
new file mode 100644
index 00000000000..3762c79d4f5
--- /dev/null
+++ b/llvm/test/CodeGen/Hexagon/rdf-dead-loop.ll
@@ -0,0 +1,31 @@
+; RUN: llc -march=hexagon < %s | FileCheck %s
+; CHECK-NOT: ={{.*}}add
+; CHECK-NOT: mem{{[bdhwu]}}
+
+define void @main() #0 {
+entry:
+  br label %body
+
+body:
+  %ip_vec30 = phi <2 x i32> [ %ip_vec, %body ], [ zeroinitializer, %entry ]
+  %scevgep.phi = phi i32* [ %scevgep.inc, %body ], [ undef, %entry ]
+  %polly.indvar = phi i32 [ %polly.indvar_next, %body ], [ 0, %entry ]
+  %vector_ptr = bitcast i32* %scevgep.phi to <2 x i32>*
+  %_p_vec_full = load <2 x i32>, <2 x i32>* %vector_ptr, align 8
+  %ip_vec = add <2 x i32> %_p_vec_full, %ip_vec30
+  %polly.indvar_next = add nsw i32 %polly.indvar, 2
+  %polly.loop_cond = icmp slt i32 %polly.indvar, 4
+  %scevgep.inc = getelementptr i32, i32* %scevgep.phi, i32 2
+  br i1 %polly.loop_cond, label %body, label %exit
+
+exit:
+  %0 = extractelement <2 x i32> %ip_vec, i32 1
+  ret void
+
+}
+
+attributes #0 = { "less-precise-fpmad"="false" "no-frame-pointer-elim"="true" "no-frame-pointer-elim-non-leaf"="true" "no-infs-fp-math"="false" "no-nans-fp-math"="false" "unsafe-fp-math"="false" "use-soft-float"="false" }
+
+!0 = !{!"int", !1}
+!1 = !{!"omnipotent char", !2}
+!2 = !{!"Simple C/C++ TBAA"}