[AsmParser] Correctly handle .ifeqs nested in other conditional directives

[ostannard]

The parser function used for the .ifeqs and .ifnes directives was missing the check for whether we are currently in an ignored block of an outer conditional directive, causing the block to be evaluated when it should not, for example:

.if 0
.ifeqs "a", "a"
// Should not be evaluated, but is
nop
.endif
.endif

[llvmbot]

@llvm/pr-subscribers-mc

Author: Oliver Stannard (ostannard)

Changes

The parser function used for the .ifeqs and .ifnes directives was missing the check for whether we are currently in an ignored block of an outer conditional directive, causing the block to be evaluated when it should not, for example:

.if 0
.ifeqs "a", "a"
// Should not be evaluated, but is
nop
.endif
.endif

---

Full diff: https://github.com/llvm/llvm-project/pull/132713.diff

3 Files Affected:

• (modified) llvm/lib/MC/MCParser/AsmParser.cpp (+30-25)
• (modified) llvm/test/MC/AsmParser/ifeqs.s (+11)
• (modified) llvm/test/MC/AsmParser/ifnes.s (+10)

diff --git a/llvm/lib/MC/MCParser/AsmParser.cpp b/llvm/lib/MC/MCParser/AsmParser.cpp
index c11c01e52fc2e..b0f0c5e5db2ce 100644
--- a/llvm/lib/MC/MCParser/AsmParser.cpp
+++ b/llvm/lib/MC/MCParser/AsmParser.cpp
@@ -5224,37 +5224,42 @@ bool AsmParser::parseDirectiveIfc(SMLoc DirectiveLoc, bool ExpectEqual) {
 /// parseDirectiveIfeqs
 ///   ::= .ifeqs string1, string2
 bool AsmParser::parseDirectiveIfeqs(SMLoc DirectiveLoc, bool ExpectEqual) {
-  if (Lexer.isNot(AsmToken::String)) {
-    if (ExpectEqual)
-      return TokError("expected string parameter for '.ifeqs' directive");
-    return TokError("expected string parameter for '.ifnes' directive");
-  }
+  TheCondStack.push_back(TheCondState);
+  TheCondState.TheCond = AsmCond::IfCond;
 
-  StringRef String1 = getTok().getStringContents();
-  Lex();
+  if (TheCondState.Ignore) {
+    eatToEndOfStatement();
+  } else {
+    if (Lexer.isNot(AsmToken::String)) {
+      if (ExpectEqual)
+        return TokError("expected string parameter for '.ifeqs' directive");
+      return TokError("expected string parameter for '.ifnes' directive");
+    }
 
-  if (Lexer.isNot(AsmToken::Comma)) {
-    if (ExpectEqual)
-      return TokError(
-          "expected comma after first string for '.ifeqs' directive");
-    return TokError("expected comma after first string for '.ifnes' directive");
-  }
+    StringRef String1 = getTok().getStringContents();
+    Lex();
 
-  Lex();
+    if (Lexer.isNot(AsmToken::Comma)) {
+      if (ExpectEqual)
+        return TokError(
+            "expected comma after first string for '.ifeqs' directive");
+      return TokError("expected comma after first string for '.ifnes' directive");
+    }
 
-  if (Lexer.isNot(AsmToken::String)) {
-    if (ExpectEqual)
-      return TokError("expected string parameter for '.ifeqs' directive");
-    return TokError("expected string parameter for '.ifnes' directive");
-  }
+    Lex();
 
-  StringRef String2 = getTok().getStringContents();
-  Lex();
+    if (Lexer.isNot(AsmToken::String)) {
+      if (ExpectEqual)
+        return TokError("expected string parameter for '.ifeqs' directive");
+      return TokError("expected string parameter for '.ifnes' directive");
+    }
 
-  TheCondStack.push_back(TheCondState);
-  TheCondState.TheCond = AsmCond::IfCond;
-  TheCondState.CondMet = ExpectEqual == (String1 == String2);
-  TheCondState.Ignore = !TheCondState.CondMet;
+    StringRef String2 = getTok().getStringContents();
+    Lex();
+
+    TheCondState.CondMet = ExpectEqual == (String1 == String2);
+    TheCondState.Ignore = !TheCondState.CondMet;
+  }
 
   return false;
 }
diff --git a/llvm/test/MC/AsmParser/ifeqs.s b/llvm/test/MC/AsmParser/ifeqs.s
index 05a26a237fcd3..fd5f1a84980a2 100644
--- a/llvm/test/MC/AsmParser/ifeqs.s
+++ b/llvm/test/MC/AsmParser/ifeqs.s
@@ -18,3 +18,14 @@
 // CHECK-NOT: .byte 0
 // CHECK: .byte 1
 
+
+.if 0
+  .ifeqs "alpha", "alpha"
+    .byte 2
+  .else
+    .byte 3
+  .endif
+.endif
+
+// CHECK-NOT: .byte 2
+// CHECK-NOT: .byte 3
diff --git a/llvm/test/MC/AsmParser/ifnes.s b/llvm/test/MC/AsmParser/ifnes.s
index 7a3cbe0264e1b..bd7dc3b637b21 100644
--- a/llvm/test/MC/AsmParser/ifnes.s
+++ b/llvm/test/MC/AsmParser/ifnes.s
@@ -20,3 +20,13 @@
 # CHECK: .byte 1
 .ifnes "equal", "equal" ; .byte 0 ; .else ; .byte 1 ; .endif
 
+.if 0
+  .ifnes "alpha", "alpha"
+    .byte 2
+  .else
+    .byte 3
+  .endif
+.endif
+
+// CHECK-NOT: .byte 2
+// CHECK-NOT: .byte 3

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[smithp35]

LGTM. Every other parseDirectiveIf follows the proposed change.