Fix a crash in MergeFunctions related to ordering of weak/strong functions

The assumption, made in insert() that weak functions are always inserted after strong functions,
is only true in the first round of adding functions.
In subsequent rounds this is no longer guaranteed , because we might remove a strong function from the tree (because it's modified) and add it later,
where an equivalent weak function already exists in the tree.
This change removes the assert in insert() and explicitly enforces a weak->strong order.
This also removes the need of two separate loops in runOnModule().

llvm-svn: 271299

1 files changed, 47 insertions, 0 deletions

diff --git a/llvm/test/Transforms/MergeFunc/merge-weak-crash.ll b/llvm/test/Transforms/MergeFunc/merge-weak-crash.ll
new file mode 100644
index 00000000000..9d2c5caa4e5
--- /dev/null
+++ b/llvm/test/Transforms/MergeFunc/merge-weak-crash.ll
@@ -0,0 +1,47 @@
+; RUN: opt -S -mergefunc < %s | FileCheck %s
+
+; CHECK-LABEL: define i32 @func1
+; CHECK: call i32 @func2
+; CHECK: ret
+
+; CHECK-LABEL: define i32 @func2
+; CHECK: call i32 @unknown
+; CHECK: ret
+
+; CHECK-LABEL: define i32 @func4
+; CHECK: call i32 @func2
+; CHECK: ret
+
+; CHECK-LABEL: define weak i32 @func3_weak
+; CHECK: call i32 @func1
+; CHECK: ret
+
+define i32 @func1(i32 %x, i32 %y) {
+  %sum = add i32 %x, %y
+  %sum2 = add i32 %sum, %y
+  %sum3 = call i32 @func4(i32 %sum, i32 %sum2)
+  ret i32 %sum3
+}
+
+define i32 @func4(i32 %x, i32 %y) {
+  %sum = add i32 %x, %y
+  %sum2 = add i32 %sum, %y
+  %sum3 = call i32 @unknown(i32 %sum, i32 %sum2)
+  ret i32 %sum3
+}
+
+define weak i32 @func3_weak(i32 %x, i32 %y) {
+  %sum = add i32 %x, %y
+  %sum2 = add i32 %sum, %y
+  %sum3 = call i32 @func2(i32 %sum, i32 %sum2)
+  ret i32 %sum3
+}
+
+define i32 @func2(i32 %x, i32 %y) {
+  %sum = add i32 %x, %y
+  %sum2 = add i32 %sum, %y
+  %sum3 = call i32 @unknown(i32 %sum, i32 %sum2)
+  ret i32 %sum3
+}
+
+declare i32 @unknown(i32 %x, i32 %y)