Added a check in the preRA scheduler for potential interference on a

induction variable. The preRA scheduler is unaware of induction vars,
so we look for potential "virtual register cycles" instead.

Fixes <rdar://problem/8946719> Bad scheduling prevents coalescing


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@129100 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 31 insertions, 0 deletions

diff --git a/test/CodeGen/ARM/2011-04-07-schediv.ll b/test/CodeGen/ARM/2011-04-07-schediv.ll
new file mode 100644
index 0000000..a61908f
--- /dev/null
+++ b/test/CodeGen/ARM/2011-04-07-schediv.ll
@@ -0,0 +1,31 @@
+; RUN: llc < %s -mcpu=cortex-a8 | FileCheck %s
+; Tests preRAsched support for VRegCycle interference.
+
+target datalayout = "e-p:32:32:32-i1:8:32-i8:8:32-i16:16:32-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:32:64-v128:32:128-a0:0:32-n32"
+target triple = "thumbv7-apple-darwin10"
+
+define void @t(i32 %src_width, float* nocapture %src_copy_start, float* nocapture %dst_copy_start, i32 %src_copy_start_index) nounwind optsize {
+entry:
+  %src_copy_start6 = bitcast float* %src_copy_start to i8*
+  %0 = icmp eq i32 %src_width, 0
+  br i1 %0, label %return, label %bb
+
+; Make sure the scheduler schedules all uses of the preincrement
+; induction variable before defining the postincrement value.
+; CHECK: t:
+; CHECK-NOT: mov
+bb:                                               ; preds = %entry, %bb
+  %j.05 = phi i32 [ %2, %bb ], [ 0, %entry ]
+  %tmp = mul i32 %j.05, %src_copy_start_index
+  %uglygep = getelementptr i8* %src_copy_start6, i32 %tmp
+  %src_copy_start_addr.04 = bitcast i8* %uglygep to float*
+  %dst_copy_start_addr.03 = getelementptr float* %dst_copy_start, i32 %j.05
+  %1 = load float* %src_copy_start_addr.04, align 4
+  store float %1, float* %dst_copy_start_addr.03, align 4
+  %2 = add i32 %j.05, 1
+  %exitcond = icmp eq i32 %2, %src_width
+  br i1 %exitcond, label %return, label %bb
+
+return:                                           ; preds = %bb, %entry
+  ret void
+}