Implement PR3495: local spiller optimization. The local spiller can now keep availability information over BB boundaries. It visits BB's in depth first order. After visiting a BB if it find a successor which has a single predecessor it visits the successor next without clearing the availability information. This allows the successor to omit reloads or change them into copies.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64298 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/CodeGen/X86/pr3495.ll b/test/CodeGen/X86/pr3495.ll
new file mode 100644
index 0000000..b7330db
--- /dev/null
+++ b/test/CodeGen/X86/pr3495.ll
@@ -0,0 +1,78 @@
+; RUN: llvm-as < %s | llc -march=x86 -stats |& grep {Number of reloads omited}
+; RUN: llvm-as < %s | llc -march=x86 -stats |& grep {Number of available reloads turned into copies}
+; PR3495
+
+target triple = "i386-pc-linux-gnu"
+@x = external global [8 x i32], align 32 ; <[8 x i32]*> [#uses=1]
+@rows = external global [8 x i32], align 32 ; <[8 x i32]*> [#uses=2]
+@up = external global [15 x i32], align 32 ; <[15 x i32]*> [#uses=2]
+@down = external global [15 x i32], align 32 ; <[15 x i32]*> [#uses=1]
+
+define i32 @queens(i32 %c) nounwind {
+entry:
+ %tmp91 = add i32 %c, 1 ; <i32> [#uses=3]
+ %tmp135 = getelementptr [8 x i32]* @x, i32 0, i32 %tmp91 ; <i32*> [#uses=1]
+ br label %bb
+
+bb: ; preds = %bb569, %entry
+ %r25.0.reg2mem.0 = phi i32 [ 0, %entry ], [ %indvar.next715, %bb569 ] ; <i32> [#uses=4]
+ %tmp27 = getelementptr [8 x i32]* @rows, i32 0, i32 %r25.0.reg2mem.0 ; <i32*> [#uses=1]
+ %tmp28 = load i32* %tmp27, align 4 ; <i32> [#uses=1]
+ %tmp29 = icmp eq i32 %tmp28, 0 ; <i1> [#uses=1]
+ br i1 %tmp29, label %bb569, label %bb31
+
+bb31: ; preds = %bb
+ %tmp35 = sub i32 %r25.0.reg2mem.0, 0 ; <i32> [#uses=1]
+ %tmp36 = getelementptr [15 x i32]* @up, i32 0, i32 %tmp35 ; <i32*> [#uses=1]
+ %tmp37 = load i32* %tmp36, align 4 ; <i32> [#uses=1]
+ %tmp38 = icmp eq i32 %tmp37, 0 ; <i1> [#uses=1]
+ br i1 %tmp38, label %bb569, label %bb41
+
+bb41: ; preds = %bb31
+ %tmp54 = sub i32 %r25.0.reg2mem.0, %c ; <i32> [#uses=1]
+ %tmp55 = add i32 %tmp54, 7 ; <i32> [#uses=1]
+ %tmp62 = getelementptr [15 x i32]* @up, i32 0, i32 %tmp55 ; <i32*> [#uses=2]
+ store i32 0, i32* %tmp62, align 4
+ br label %bb92
+
+bb92: ; preds = %bb545, %bb41
+ %r20.0.reg2mem.0 = phi i32 [ 0, %bb41 ], [ %indvar.next711, %bb545 ] ; <i32> [#uses=5]
+ %tmp94 = getelementptr [8 x i32]* @rows, i32 0, i32 %r20.0.reg2mem.0 ; <i32*> [#uses=1]
+ %tmp95 = load i32* %tmp94, align 4 ; <i32> [#uses=0]
+ %tmp112 = add i32 %r20.0.reg2mem.0, %tmp91 ; <i32> [#uses=1]
+ %tmp113 = getelementptr [15 x i32]* @down, i32 0, i32 %tmp112 ; <i32*> [#uses=2]
+ %tmp114 = load i32* %tmp113, align 4 ; <i32> [#uses=1]
+ %tmp115 = icmp eq i32 %tmp114, 0 ; <i1> [#uses=1]
+ br i1 %tmp115, label %bb545, label %bb118
+
+bb118: ; preds = %bb92
+ %tmp122 = sub i32 %r20.0.reg2mem.0, %tmp91 ; <i32> [#uses=0]
+ store i32 0, i32* %tmp113, align 4
+ store i32 %r20.0.reg2mem.0, i32* %tmp135, align 4
+ br label %bb142
+
+bb142: ; preds = %bb142, %bb118
+ %k18.0.reg2mem.0 = phi i32 [ 0, %bb118 ], [ %indvar.next709, %bb142 ] ; <i32> [#uses=1]
+ %indvar.next709 = add i32 %k18.0.reg2mem.0, 1 ; <i32> [#uses=2]
+ %exitcond710 = icmp eq i32 %indvar.next709, 8 ; <i1> [#uses=1]
+ br i1 %exitcond710, label %bb155, label %bb142
+
+bb155: ; preds = %bb142
+ %tmp156 = tail call i32 @putchar(i32 10) nounwind ; <i32> [#uses=0]
+ br label %bb545
+
+bb545: ; preds = %bb155, %bb92
+ %indvar.next711 = add i32 %r20.0.reg2mem.0, 1 ; <i32> [#uses=2]
+ %exitcond712 = icmp eq i32 %indvar.next711, 8 ; <i1> [#uses=1]
+ br i1 %exitcond712, label %bb553, label %bb92
+
+bb553: ; preds = %bb545
+ store i32 1, i32* %tmp62, align 4
+ br label %bb569
+
+bb569: ; preds = %bb553, %bb31, %bb
+ %indvar.next715 = add i32 %r25.0.reg2mem.0, 1 ; <i32> [#uses=1]
+ br label %bb
+}
+
+declare i32 @putchar(i32)