[LLD] [MinGW] Hook up --icf=safe to -opt:safeicf (#70037)

Back when the --icf= option was hooked up in the MinGW frontend in LLD,
in 2017, lld-link didn't support safe ICF, and mapping it to noicf was
suggested in review: https://reviews.llvm.org/D40019

In 2018, in ab03802,
lld-link did get support for handling address significance tables,
allowing the ICF to operate safely on more sections.

Later in 2021, lld-link did get support for a separate safe ICF mode in
5bdc5e7 /
https://reviews.llvm.org/D97436.

Hook this up for the MinGW frontend as well.

Author: mstorsjo

lld/MinGW/Driver.cpp

@@ -375,7 +375,9 @@ bool link(ArrayRef<const char *> argsArr, llvm::raw_ostream &stdoutOS,
     StringRef s = a->getValue();
     if (s == "all")
       add("-opt:icf");
-    else if (s == "safe" || s == "none")
+    else if (s == "safe")
+      add("-opt:safeicf");
+    else if (s == "none")
       add("-opt:noicf");
     else
       error("unknown parameter: --icf=" + s);

lld/test/MinGW/driver.test

@@ -205,10 +205,12 @@ GC-SECTIONS: -opt:ref
 RUN: ld.lld -### -m i386pep foo.o 2>&1 | FileCheck -check-prefix ICF-NONE %s
 RUN: ld.lld -### -m i386pep foo.o --icf=none 2>&1 | FileCheck -check-prefix ICF-NONE %s
 RUN: ld.lld -### -m i386pep foo.o -icf=none 2>&1 | FileCheck -check-prefix ICF-NONE %s
-RUN: ld.lld -### -m i386pep foo.o --icf=safe 2>&1 | FileCheck -check-prefix ICF-NONE %s
-RUN: ld.lld -### -m i386pep foo.o -icf=safe 2>&1 | FileCheck -check-prefix ICF-NONE %s
 ICF-NONE: -opt:noicf
 
+RUN: ld.lld -### -m i386pep foo.o --icf=safe 2>&1 | FileCheck -check-prefix ICF-SAFE %s
+RUN: ld.lld -### -m i386pep foo.o -icf=safe 2>&1 | FileCheck -check-prefix ICF-SAFE %s
+ICF-SAFE: -opt:safeicf
+
 RUN: ld.lld -### -m i386pep foo.o --icf=all 2>&1 | FileCheck -check-prefix ICF %s
 RUN: ld.lld -### -m i386pep foo.o -icf=all 2>&1 | FileCheck -check-prefix ICF %s
 RUN: ld.lld -### -m i386pep foo.o --icf all 2>&1 | FileCheck -check-prefix ICF %s