R600/SI: Enable selecting SALU inside branches

We can do this now that the FixSGPRLiveRanges pass is working.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218353 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/R600/sgpr-control-flow.ll

@@ -4,9 +4,14 @@
 ; Most SALU instructions ignore control flow, so we need to make sure
 ; they don't overwrite values from other blocks.
 
-; SI-NOT: S_ADD
+; If the branch decision is made based on a value in an SGPR then all
+; threads will execute the same code paths, so we don't need to worry
+; about instructions in different blocks overwriting each other.
+; SI-LABEL: @sgpr_if_else_salu_br
+; SI: S_ADD
+; SI: S_ADD
 
-define void @sgpr_if_else(i32 addrspace(1)* %out, i32 %a, i32 %b, i32 %c, i32 %d, i32 %e) {
+define void @sgpr_if_else_salu_br(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
@@ -25,3 +30,35 @@ endif:
   store i32 %4, i32 addrspace(1)* %out
   ret void
 }
+
+; The two S_ADD instructions should write to different registers, since
+; different threads will take different control flow paths.
+
+; SI-LABEL: @sgpr_if_else_valu_br
+; SI: S_ADD_I32 [[SGPR:s[0-9]+]]
+; SI-NOT: S_ADD_I32 [[SGPR]]
+
+define void @sgpr_if_else_valu_br(i32 addrspace(1)* %out, float %a, i32 %b, i32 %c, i32 %d, i32 %e) {
+entry:
+  %tid = call i32 @llvm.r600.read.tidig.x() #0
+  %tid_f = uitofp i32 %tid to float
+  %tmp1 = fcmp ueq float %tid_f, 0.0
+  br i1 %tmp1, label %if, label %else
+
+if:
+  %tmp2 = add i32 %b, %c
+  br label %endif
+
+else:
+  %tmp3 = add i32 %d, %e
+  br label %endif
+
+endif:
+  %tmp4 = phi i32 [%tmp2, %if], [%tmp3, %else]
+  store i32 %tmp4, i32 addrspace(1)* %out
+  ret void
+}
+
+declare i32 @llvm.r600.read.tidig.x() #0
+
+attributes #0 = { readnone }