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

1 files changed, 78 insertions, 0 deletions

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)