Implement split-sections support for windows.

Summary:
Initial implementation of split-section on Windows.

This also corrects section namings and uses the platform
convention of `$` instead of `.` to separate sections.

Implementation is based on @awson's patches to binutils.

Binutils requires some extra help when compiling the libraries
for GHCi usage. We drop the `-T` and use implicit scripts to amend
the linker scripts instead of replacing it.

Because of these very large GHCi object files, we need big-obj support,
which will be added by another patch.

Test Plan: ./validate

Reviewers: awson, austin, bgamari

Subscribers: dfeuer, rwbarton, thomie, snowleopard, #ghc_windows_task_force

GHC Trac Issues: #12913

Differential Revision: https://phabricator.haskell.org/D3383

1 files changed, 26 insertions, 0 deletions

diff --git a/driver/utils/merge_sections_pe.ld b/driver/utils/merge_sections_pe.ld
new file mode 100644
index 0000000000..c9eed87ced
--- /dev/null
+++ b/driver/utils/merge_sections_pe.ld
@@ -0,0 +1,26 @@
+/* Linker script to undo -split-sections and merge all sections together when
+ * linking relocatable object files for GHCi.
+ * ld -r normally retains the individual sections, which is what you would want
+ * if the intention is to eventually link into a binary with --gc-sections, but
+ * it doesn't have a flag for directly doing what we want. */
+SECTIONS
+{
+    .text : {
+        *(.text$*)
+    }
+    .rdata : {
+        *(.rdata$*)
+    }
+    .data : {
+        *(.data$*)
+    }
+    .pdata : {
+        *(.pdata$*)
+    }
+    .xdata : {
+        *(.xdata$*)
+    }
+    .bss : {
+        *(.bss$*)
+    }
+}