5 files changed, 9 insertions, 0 deletions
diff --git a/decl.h b/decl.h
index 5b8b83d..db6a28c 100644
--- a/decl.h
+++ b/decl.h
@@ -20,6 +20,7 @@ enum builtinkind {
 	BUILTINVAEND,
 	BUILTINOFFSETOF,
 	BUILTINALLOCA,
+	BUILTININFF,
 };
 
 struct declaration {
diff --git a/expr.c b/expr.c
index 30399e5..8e8a7ca 100644
--- a/expr.c
+++ b/expr.c
@@ -481,6 +481,11 @@ postfixexpr(struct scope *s, struct expression *r)
 					e->builtin.kind = BUILTINALLOCA;
 					e->builtin.arg = exprconvert(assignexpr(s), &typeulong);
 					break;
+				case BUILTININFF:
+					e = mkexpr(EXPRCONST, &typefloat, 0);
+					/* TODO: use INFINITY here when we can handle musl's math.h */
+					e->constant.f = strtod("inf", NULL);
+					break;
 				default:
 					fatal("internal error; unknown builtin");
 				}
diff --git a/scope.c b/scope.c
index bd550e8..00569b9 100644
--- a/scope.c
+++ b/scope.c
@@ -24,6 +24,7 @@ scopeinit(void)
 		{"__builtin_va_end",   {.kind = DECLBUILTIN, .builtin = BUILTINVAEND}},
 		{"__builtin_offsetof", {.kind = DECLBUILTIN, .builtin = BUILTINOFFSETOF}},
 		{"__builtin_alloca",   {.kind = DECLBUILTIN, .builtin = BUILTINALLOCA}},
+		{"__builtin_inff",     {.kind = DECLBUILTIN, .builtin = BUILTININFF}},
 	};
 	struct builtin *b;
 
diff --git a/tests/builtin-inff.c b/tests/builtin-inff.c
new file mode 100644
index 0000000..2dcd040
--- /dev/null
+++ b/tests/builtin-inff.c
@@ -0,0 +1 @@
+float x = __builtin_inff();
diff --git a/tests/builtin-inff.qbe b/tests/builtin-inff.qbe
new file mode 100644
index 0000000..5eb8060
--- /dev/null
+++ b/tests/builtin-inff.qbe
@@ -0,0 +1 @@
+export data $x = align 4 { s s_inf, }