IR: Implement uselistorder assembly directives

Implement `uselistorder` and `uselistorder_bb` assembly directives,
which allow the use-list order to be recovered when round-tripping to
assembly.

This is the bulk of PR20515.

llvm-svn: 216025

1 files changed, 37 insertions, 0 deletions

diff --git a/llvm/test/Assembler/invalid-uselistorder-function-between-blocks.ll b/llvm/test/Assembler/invalid-uselistorder-function-between-blocks.ll
new file mode 100644
index 00000000000..8f771e86dd4
--- /dev/null
+++ b/llvm/test/Assembler/invalid-uselistorder-function-between-blocks.ll
@@ -0,0 +1,37 @@
+; RUN: not llvm-as < %s -disable-output 2>&1 | FileCheck %s
+; CHECK: error: expected uselistorder directive
+
+define i32 @f32(i32 %a, i32 %b, i32 %c, i32 %d) {
+entry:
+  br label %first
+
+; <label 0>:
+  %eh = mul i32 %e, %1
+  %sum = add i32 %eh, %ef
+  br label %preexit
+
+preexit:
+  %product = phi i32 [%ef, %first], [%sum, %0]
+  %backto0 = icmp slt i32 %product, -9
+  br i1 %backto0, label %0, label %exit
+
+first:
+  %e = add i32 %a, 7
+  %f = add i32 %b, 7
+  %g = add i32 %c, 8
+  %1 = add i32 %d, 8
+  %ef = mul i32 %e, %f
+  %g1 = mul i32 %g, %1
+  %goto0 = icmp slt i32 %g1, -9
+  br i1 %goto0, label %0, label %preexit
+
+; uselistorder directives
+  uselistorder i32 7, { 1, 0 }
+  uselistorder i32 %1, { 1, 0 }
+  uselistorder i32 %e, { 1, 0 }
+  uselistorder label %0, { 1, 0 }
+  uselistorder label %preexit, { 1, 0 }
+
+exit:
+  ret i32 %product
+}