BranchProb: modify the definition of an edge in BranchProbabilityInfo to handle

the case of multiple edges from one block to another.

A simple example is a switch statement with multiple values to the same
destination. The definition of an edge is modified from a pair of blocks to
a pair of PredBlock and an index into the successors.

Also set the weight correctly when building SelectionDAG from LLVM IR,
especially when converting a Switch.
IntegersSubsetMapping is updated to calculate the weight for each cluster.

llvm-svn: 162572

1 files changed, 32 insertions, 0 deletions

diff --git a/llvm/test/CodeGen/Generic/MachineBranchProb.ll b/llvm/test/CodeGen/Generic/MachineBranchProb.ll
new file mode 100644
index 00000000000..802ee2cb055
--- /dev/null
+++ b/llvm/test/CodeGen/Generic/MachineBranchProb.ll
@@ -0,0 +1,32 @@
+; RUN: llc < %s -print-machineinstrs=expand-isel-pseudos -o /dev/null 2>&1 | FileCheck %s
+
+; Make sure we have the correct weight attached to each successor.
+define i32 @test2(i32 %x) nounwind uwtable readnone ssp {
+; CHECK: Machine code for function test2:
+entry:
+  %conv = sext i32 %x to i64
+  switch i64 %conv, label %return [
+    i64 0, label %sw.bb
+    i64 1, label %sw.bb
+    i64 4, label %sw.bb
+    i64 5, label %sw.bb1
+  ], !prof !0
+; CHECK: BB#0: derived from LLVM BB %entry
+; CHECK: Successors according to CFG: BB#2(64) BB#4(14)
+; CHECK: BB#4: derived from LLVM BB %entry
+; CHECK: Successors according to CFG: BB#1(10) BB#5(4)
+; CHECK: BB#5: derived from LLVM BB %entry
+; CHECK: Successors according to CFG: BB#1(4) BB#3(7)
+
+sw.bb:
+  br label %return
+
+sw.bb1:
+  br label %return
+
+return:
+  %retval.0 = phi i32 [ 5, %sw.bb1 ], [ 1, %sw.bb ], [ 0, %entry ]
+  ret i32 %retval.0
+}
+
+!0 = metadata !{metadata !"branch_weights", i32 7, i32 6, i32 4, i32 4, i32 64}