[ELF] - Implemented comparsion operators for linkerscript

[grimar]

Summary

Patch implements <,>,!=,==,>=,<= operators.
Actually in freebsd scripts I think I saw only != operator,
but since it is easy to support all at once - desided to do that.

[emaste]

ELF/LinkerScript.cpp

152 ↗

(On Diff #54671)

Trivial comment, but why not L != R here? And, why not just return L < R;, return L > R; etc. in general? For me at least ? 1 : 0 is not any more clear/readable.

[grimar]

ELF/LinkerScript.cpp

152 ↗

(On Diff #54671)

I think you right. I`ll change that.

[grimar]

• Addressed comment from Ed.

[ruiu]

ELF/LinkerScript.cpp

51–61 ↗

(On Diff #54674)

These operator precedences are not correct. * and / should have the same precedence, and so are + and -. & has lower precedence over comparison operators.

https://www.sourceware.org/binutils/docs-2.10/ld_3.html#SEC45

[ruiu]

ELF/LinkerScript.cpp

51–61 ↗

(On Diff #54674)

Also, please don't use precedence 0. We pass 0 as the minimum precedence in parseExpr. It doesn't expect that there is an operator with precedence 0.

[grimar]

ELF/LinkerScript.cpp

51–61 ↗

(On Diff #54674)

Yes, I messed up these accidentally :( will fix.

[grimar]

• Addressed review comments.

ELF/LinkerScript.cpp

51–61 ↗

(On Diff #54674)

I used c++ precedence for added ones, btw: http://en.cppreference.com/w/cpp/language/operator_precedence.
It is a bit different about == and !=.
And I just missed that & should have lower precedence than them all.

[ruiu]

LGTM with a nit.

ELF/LinkerScript.cpp

121–147 ↗

(On Diff #54734)

Let's sort them in the same order as the operator precedence.

lld/trunk/ELF/LinkerScript.cpp

private:
 
   uint64_t Dot;
 };
 }
 
 static int precedence(StringRef Op) {
   return StringSwitch<int>(Op)
       .Case("*", 4)
-      .Case("/", 3)
-      .Case("+", 2)
-      .Case("-", 2)
+      .Case("/", 4)
+      .Case("+", 3)
+      .Case("-", 3)
+      .Case("<", 2)
+      .Case(">", 2)
+      .Case(">=", 2)
+      .Case("<=", 2)
+      .Case("==", 2)
+      .Case("!=", 2)
       .Case("&", 1)
       .Default(-1);
 }
 
 static uint64_t evalExpr(std::vector<StringRef> &Tokens, uint64_t Dot) {
   return ExprParser(Tokens, Dot).run();
 }
 
uint64_t ExprParser::parseTernary(uint64_t Cond) {
   next();
   uint64_t V = parseExpr();
   expect(":");
   uint64_t W = parseExpr();
   return Cond ? V : W;
 }
 
 uint64_t ExprParser::apply(StringRef Op, uint64_t L, uint64_t R) {
-  if (Op == "+")
-    return L + R;
-  if (Op == "-")
-    return L - R;
   if (Op == "*")
     return L * R;
   if (Op == "/") {
     if (R == 0) {
       error("division by zero");
       return 0;
     }
     return L / R;
   }
+  if (Op == "+")
+    return L + R;
+  if (Op == "-")
+    return L - R;
+  if (Op == "<")
+    return L < R;
+  if (Op == ">")
+    return L > R;
+  if (Op == ">=")
+    return L >= R;
+  if (Op == "<=")
+    return L <= R;
+  if (Op == "==")
+    return L == R;
+  if (Op == "!=")
+    return L != R;
   if (Op == "&")
     return L & R;
   llvm_unreachable("invalid operator");
   return 0;
 }
 
 // This is a part of the operator-precedence parser.
 // This function assumes that the remaining token stream starts

lld/trunk/ELF/ScriptParser.cpp

if (S.startswith("\"")) {
       Ret.push_back(S.substr(1, E - 1));
       S = S.substr(E + 1);
       continue;
     }
 
     // Unquoted token
     size_t Pos = S.find_first_not_of(
         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
-        "0123456789_.$/\\~=+[]*?-:");
+        "0123456789_.$/\\~=+[]*?-:!<>");
     // A character that cannot start a word (which is usually a
     // punctuation) forms a single character token.
     if (Pos == 0)
       Pos = 1;
     Ret.push_back(S.substr(0, Pos));
     S = S.substr(Pos);
   }
 }

lld/trunk/test/ELF/linkerscript-locationcounter.s

 # RUN:  . = 0x10000 + (0x1000 + 0x1000) * 0x2; \
 # RUN:  .bracket : { *(.bracket) } \
 # RUN:  . = 0x17000 & 0x15000; \
 # RUN:  .and : { *(.and) } \
 # RUN:  . = 0x1 ? 0x16000 : 0x999999; \
 # RUN:  .ternary1 : { *(.ternary1) } \
 # RUN:  . = 0x0 ? 0x999999 : 0x17000; \
 # RUN:  .ternary2 : { *(.ternary2) } \
+# RUN:  . = 0x0 < 0x1 ? 0x18000 : 0x999999; \
+# RUN:  .less : { *(.less) } \
+# RUN:  . = 0x1 <= 0x1 ? 0x19000 : 0x999999; \
+# RUN:  .lesseq : { *(.lesseq) } \
+# RUN:  . = 0x1 > 0x0 ? 0x20000 : 0x999999; \
+# RUN:  .great : { *(.great) } \
+# RUN:  . = 0x1 >= 0x1 ? 0x21000 : 0x999999; \
+# RUN:  .greateq : { *(.greateq) } \
+# RUN:  . = 0x1 == 0x1 ? 0x22000 : 0x999999; \
+# RUN:  .eq : { *(.eq) } \
+# RUN:  . = 0x2 != 0x1 ? 0x23000 : 0x999999; \
+# RUN:  .neq : { *(.neq) } \
 # RUN: }" > %t.script
 # RUN: ld.lld %t --script %t.script -o %t2
 # RUN: llvm-readobj -s %t2 | FileCheck %s
 
 # CHECK: Section {
 # CHECK:   Index: 1
 # CHECK:   Name: .plus
 # CHECK-NEXT:   Type: SHT_PROGBITS

 # CHECK-NEXT:   Address: 0x17000
 # CHECK-NEXT:   Offset:
 # CHECK-NEXT:   Size:
 # CHECK-NEXT:   Link:
 # CHECK-NEXT:   Info:
 # CHECK-NEXT:   AddressAlignment:
 # CHECK-NEXT:   EntrySize:
 # CHECK-NEXT: }
+# CHECK-NEXT: Section {
+# CHECK-NEXT:   Index:
+# CHECK-NEXT:   Name: .less
+# CHECK-NEXT:   Type: SHT_PROGBITS
+# CHECK-NEXT:   Flags [
+# CHECK-NEXT:     SHF_ALLOC
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Address: 0x18000
+# CHECK-NEXT:   Offset:
+# CHECK-NEXT:   Size:
+# CHECK-NEXT:   Link:
+# CHECK-NEXT:   Info:
+# CHECK-NEXT:   AddressAlignment:
+# CHECK-NEXT:   EntrySize:
+# CHECK-NEXT: }
+# CHECK-NEXT: Section {
+# CHECK-NEXT:   Index:
+# CHECK-NEXT:   Name: .lesseq
+# CHECK-NEXT:   Type: SHT_PROGBITS
+# CHECK-NEXT:   Flags [
+# CHECK-NEXT:     SHF_ALLOC
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Address: 0x19000
+# CHECK-NEXT:   Offset:
+# CHECK-NEXT:   Size:
+# CHECK-NEXT:   Link:
+# CHECK-NEXT:   Info:
+# CHECK-NEXT:   AddressAlignment:
+# CHECK-NEXT:   EntrySize:
+# CHECK-NEXT: }
+# CHECK-NEXT: Section {
+# CHECK-NEXT:   Index:
+# CHECK-NEXT:   Name: .great
+# CHECK-NEXT:   Type: SHT_PROGBITS
+# CHECK-NEXT:   Flags [
+# CHECK-NEXT:     SHF_ALLOC
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Address: 0x20000
+# CHECK-NEXT:   Offset:
+# CHECK-NEXT:   Size:
+# CHECK-NEXT:   Link:
+# CHECK-NEXT:   Info:
+# CHECK-NEXT:   AddressAlignment:
+# CHECK-NEXT:   EntrySize:
+# CHECK-NEXT: }
+# CHECK-NEXT: Section {
+# CHECK-NEXT:   Index:
+# CHECK-NEXT:   Name: .greateq
+# CHECK-NEXT:   Type: SHT_PROGBITS
+# CHECK-NEXT:   Flags [
+# CHECK-NEXT:     SHF_ALLOC
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Address: 0x21000
+# CHECK-NEXT:   Offset:
+# CHECK-NEXT:   Size:
+# CHECK-NEXT:   Link:
+# CHECK-NEXT:   Info:
+# CHECK-NEXT:   AddressAlignment:
+# CHECK-NEXT:   EntrySize:
+# CHECK-NEXT: }
+# CHECK-NEXT: Section {
+# CHECK-NEXT:   Index:
+# CHECK-NEXT:   Name: .eq
+# CHECK-NEXT:   Type: SHT_PROGBITS
+# CHECK-NEXT:   Flags [
+# CHECK-NEXT:     SHF_ALLOC
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Address: 0x22000
+# CHECK-NEXT:   Offset:
+# CHECK-NEXT:   Size:
+# CHECK-NEXT:   Link:
+# CHECK-NEXT:   Info:
+# CHECK-NEXT:   AddressAlignment:
+# CHECK-NEXT:   EntrySize:
+# CHECK-NEXT: }
+# CHECK-NEXT: Section {
+# CHECK-NEXT:   Index:
+# CHECK-NEXT:   Name: .neq
+# CHECK-NEXT:   Type: SHT_PROGBITS
+# CHECK-NEXT:   Flags [
+# CHECK-NEXT:     SHF_ALLOC
+# CHECK-NEXT:   ]
+# CHECK-NEXT:   Address: 0x23000
+# CHECK-NEXT:   Offset:
+# CHECK-NEXT:   Size:
+# CHECK-NEXT:   Link:
+# CHECK-NEXT:   Info:
+# CHECK-NEXT:   AddressAlignment:
+# CHECK-NEXT:   EntrySize:
+# CHECK-NEXT: }
 
 ## Mailformed number error.
 # RUN: echo "SECTIONS { \
 # RUN:  . = 0x12Q41; \
 # RUN: }" > %t.script
 # RUN: not ld.lld %t --script %t.script -o %t2 2>&1 | \
 # RUN:  FileCheck --check-prefix=NUMERR %s
 # NUMERR: malformed number: 0x12Q41

 .section .and, "a"
 .quad 0
 
 .section .ternary1, "a"
 .quad 0
 
 .section .ternary2, "a"
 .quad 0
+
+.section .less, "a"
+.quad 0
+
+.section .lesseq, "a"
+.quad 0
+
+.section .great, "a"
+.quad 0
+
+.section .greateq, "a"
+.quad 0
+
+.section .eq, "a"
+.quad 0
+
+.section .neq, "a"
+.quad 0