Transform: add SymbolRewriter pass

This introduces the symbol rewriter. This is an IR->IR transformation that is
implemented as a CodeGenPrepare pass. This allows for the transparent
adjustment of the symbols during compilation.

It provides a clean, simple, elegant solution for symbol inter-positioning. This
technique is often used, such as in the various sanitizers and performance
analysis.

The control of this is via a custom YAML syntax map file that indicates source
to destination mapping, so as to avoid having the compiler to know the exact
details of the source to destination transformations.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221548 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 105 insertions, 0 deletions

diff --git a/test/SymbolRewriter/rewrite.ll b/test/SymbolRewriter/rewrite.ll
new file mode 100644
index 000000000000..716fff9f284c
--- /dev/null
+++ b/test/SymbolRewriter/rewrite.ll
@@ -0,0 +1,59 @@
+; RUN: opt -mtriple i686-win32 -rewrite-symbols -rewrite-map-file %p/rewrite.map \
+; RUN:   %s -o - | llvm-dis | FileCheck %s
+
+declare void @source_function()
+@source_variable = external global i32
+declare void @source_function_pattern_function()
+declare void @source_function_pattern_multiple_function_matches()
+@source_variable_pattern_variable = external global i32
+@source_variable_pattern_multiple_variable_matches = external global i32
+declare void @"\01naked_source_function"()
+declare void @"\01__imp_missing_global_leader_prefix"()
+
+declare i32 @first_callee()
+declare i32 @second_callee()
+define i32 @caller() {
+  %rhs = call i32 @first_callee()
+  %lhs = call i32 @second_callee()
+  %res = add i32 %rhs, %lhs
+  ret i32 %res
+}
+
+%struct.S = type { i8 }
+@_ZN1SC1Ev = alias void (%struct.S*)* @_ZN1SC2Ev
+define void @_ZN1SC2Ev(%struct.S* %this) unnamed_addr align 2 {
+entry:
+  %this.addr = alloca %struct.S*, align 4
+  store %struct.S* %this, %struct.S** %this.addr, align 4
+  ret void
+}
+
+; CHECK: @target_variable = external global i32
+; CHECK-NOT: @source_variable = external global i32
+; CHECK: @target_pattern_variable = external global i32
+; CHECK-NOT: @source_pattern_variable = external global i32
+; CHECK: @target_pattern_multiple_variable_matches = external global i32
+; CHECK-NOT: @source_pattern_multiple_variable_matches = external global i32
+; CHECK: declare void @target_function()
+; CHECK-NOT: declare void @source_function()
+; CHECK: declare void @target_pattern_function()
+; CHECK-NOT: declare void @source_function_pattern_function()
+; CHECK: declare void @target_pattern_multiple_function_matches()
+; CHECK-NOT: declare void @source_function_pattern_multiple_function_matches()
+; CHECK: declare void @naked_target_function()
+; CHECK-NOT: declare void @"\01naked_source_function"()
+; CHECK-NOT: declare void @"\01__imp__imported_function"()
+; CHECK: declare void @"\01__imp_missing_global_leader_prefix"()
+; CHECK-NOT: declare void @"\01__imp_DO_NOT_REWRITE"()
+
+; CHECK: declare i32 @renamed_callee()
+; CHECK-NOT: declare i32 @first_callee()
+; CHECK: declare i32 @second_callee()
+; CHECK: define i32 @caller() {
+; CHECK:   %rhs = call i32 @renamed_callee()
+; CHECK-NOT: %rhs = call i32 @first_callee()
+; CHECK:   %lhs = call i32 @second_callee()
+; CHECK:   %res = add i32 %rhs, %lhs
+; CHECK:   ret i32 %res
+; CHECK: }
+
diff --git a/test/SymbolRewriter/rewrite.map b/test/SymbolRewriter/rewrite.map
new file mode 100644
index 000000000000..ef6dfc8ca2b9
--- /dev/null
+++ b/test/SymbolRewriter/rewrite.map
@@ -0,0 +1,46 @@
+function: {
+  source: source_function,
+  target: target_function,
+}
+
+global variable: {
+  source: source_variable,
+  target: target_variable,
+}
+
+function: {
+  source: source_function_(.*),
+  transform: target_\1,
+}
+
+global variable: {
+  source: source_variable_(.*),
+  transform: target_\1,
+}
+
+function: {
+  source: naked_source_function,
+  target: naked_target_function,
+  naked: true,
+}
+
+function: {
+  source: imported_function,
+  target: exported_function,
+}
+
+function: {
+  source: missing_global_leader_prefix,
+  target: DO_NOT_REWRITE,
+}
+
+function: {
+  source: first_callee,
+  target: renamed_callee,
+}
+
+global alias: {
+  source: _ZN1SC1Ev,
+  target: _ZN1SD1Ev,
+}
+