- CodeGenPrepare does not split loop back edges but it only knows about back edges of single block loops. It now does a DFS walk to find loop back edges.

- Use SplitBlockPredecessors to factor out common predecessors of the critical edge destination. This is disabled for now due to some regressions.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61248 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 50 insertions, 0 deletions

diff --git a/test/CodeGen/X86/critical-edge-split.ll b/test/CodeGen/X86/critical-edge-split.ll
new file mode 100644
index 0000000..7b83ecb
--- /dev/null
+++ b/test/CodeGen/X86/critical-edge-split.ll
@@ -0,0 +1,50 @@
+; RUN: llvm-as < %s | llc -mtriple=i386-apple-darwin -stats -info-output-file - | grep asm-printer | grep 31
+
+	%CC = type { %Register }
+	%II = type { %"struct.XX::II::$_74" }
+	%JITFunction = type %YYValue* (%CC*, %YYValue**)
+	%YYValue = type { i32 (...)** }
+	%Register = type { %"struct.XX::ByteCodeFeatures" }
+	%"struct.XX::ByteCodeFeatures" = type { i32 }
+	%"struct.XX::II::$_74" = type { i8* }
+@llvm.used = appending global [1 x i8*] [ i8* bitcast (%JITFunction* @loop to i8*) ], section "llvm.metadata"		; <[1 x i8*]*> [#uses=0]
+
+define %YYValue* @loop(%CC*, %YYValue**) nounwind {
+; <label>:2
+	%3 = getelementptr %CC* %0, i32 -9		; <%CC*> [#uses=1]
+	%4 = bitcast %CC* %3 to %YYValue**		; <%YYValue**> [#uses=2]
+	%5 = load %YYValue** %4		; <%YYValue*> [#uses=3]
+	%unique_1.i = ptrtoint %YYValue* %5 to i1		; <i1> [#uses=1]
+	br i1 %unique_1.i, label %loop, label %11
+
+loop:		; preds = %6, %2
+	%.1 = phi %YYValue* [ inttoptr (i32 1 to %YYValue*), %2 ], [ %intAddValue, %6 ]		; <%YYValue*> [#uses=3]
+	%immediateCmp = icmp slt %YYValue* %.1, %5		; <i1> [#uses=1]
+	br i1 %immediateCmp, label %6, label %8
+
+; <label>:6		; preds = %loop
+	%lhsInt = ptrtoint %YYValue* %.1 to i32		; <i32> [#uses=1]
+	%7 = call { i32, i1 } @llvm.sadd.with.overflow.i32(i32 %lhsInt, i32 2)		; <{ i32, i1 }> [#uses=2]
+	%intAdd = extractvalue { i32, i1 } %7, 0		; <i32> [#uses=1]
+	%intAddValue = inttoptr i32 %intAdd to %YYValue*		; <%YYValue*> [#uses=1]
+	%intAddOverflow = extractvalue { i32, i1 } %7, 1		; <i1> [#uses=1]
+	br i1 %intAddOverflow, label %.loopexit, label %loop
+
+; <label>:8		; preds = %loop
+	ret %YYValue* inttoptr (i32 10 to %YYValue*)
+
+.loopexit:		; preds = %6
+	%9 = bitcast %CC* %0 to %YYValue**		; <%YYValue**> [#uses=1]
+	store %YYValue* %.1, %YYValue** %9
+	store %YYValue* %5, %YYValue** %4
+	%10 = call fastcc %YYValue* @foobar(%II* inttoptr (i32 3431104 to %II*), %CC* %0, %YYValue** %1)		; <%YYValue*> [#uses=1]
+	ret %YYValue* %10
+
+; <label>:11		; preds = %2
+	%12 = call fastcc %YYValue* @foobar(%II* inttoptr (i32 3431080 to %II*), %CC* %0, %YYValue** %1)		; <%YYValue*> [#uses=1]
+	ret %YYValue* %12
+}
+
+declare fastcc %YYValue* @foobar(%II*, %CC*, %YYValue**) nounwind
+
+declare { i32, i1 } @llvm.sadd.with.overflow.i32(i32, i32) nounwind