[lld] [LLD][RISCV] Add relaxation for absolute symbol whose hi20 can use c.lui (PR #86294)

[Philip Reames via llvm-commits]

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@@ -789,25 +791,39 @@ static void relaxTlsLe(const InputSection &sec, size_t i, uint64_t loc,
 
 static void relaxHi20Lo12(const InputSection &sec, size_t i, uint64_t loc,
                           Relocation &r, uint32_t &remove) {
-  const Defined *gp = ElfSym::riscvGlobalPointer;
-  if (!gp)
-    return;
-
-  if (!isInt<12>(r.sym->getVA(r.addend) - gp->getVA()))
+  if (const Defined *gp = ElfSym::riscvGlobalPointer;
+      gp && isInt<12>(r.sym->getVA(r.addend) - gp->getVA())) {
+    switch (r.type) {
+    case R_RISCV_RVC_LUI:
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preames wrote:

Note that the addition of the handling for R_RISCV_RVC_LUI is technically a separate change.  Previously, if a user manually wrote a c.lui relocation in the assembler (clang doesn't seem to ever emit this), and we applied gp relaxation we'd end up with a stray c.lui whose result was never read.  I noticed it while thinking through the interactions with the new code, but it could be separated if that was reviewer preference.  

https://github.com/llvm/llvm-project/pull/86294