Made changes to the previous patch to stop attaching readonly or readnone in
the following cases:
1. The inline-asm has no output operands. In this case, it is implicitly
volatile.
2. The inline-asm returns a value by-reference instead of by-value. The
previous patch wasn't catching the case where a "=r" constraint resulted in a
value being returned by-reference.
Also, fixed the test case to catch those two cases.
http://reviews.llvm.org/D10546
Files:
lib/CodeGen/CGStmt.cpp
test/CodeGen/asm-attrs.c
EMAIL PREFERENCES
http://reviews.llvm.org/settings/panel/emailpreferences/
Index: lib/CodeGen/CGStmt.cpp
===================================================================
--- lib/CodeGen/CGStmt.cpp
+++ lib/CodeGen/CGStmt.cpp
@@ -1846,6 +1846,14 @@
std::vector<llvm::Value*> InOutArgs;
std::vector<llvm::Type*> InOutArgTypes;
+ // An inline asm can be marked readonly if it meets the following conditions:
+ // - it doesn't have any sideeffects
+ // - it doesn't clobber memory
+ // - it doesn't return a value by-reference
+ // It can be marked readnone if it doesn't have any input memory constraints
+ // in addition to meeting the conditions listed above.
+ bool ReadOnly = true, ReadNone = true;
+
for (unsigned i = 0, e = S.getNumOutputs(); i != e; i++) {
TargetInfo::ConstraintInfo &Info = OutputConstraintInfos[i];
@@ -1909,6 +1917,7 @@
Args.push_back(Dest.getAddress());
Constraints += "=*";
Constraints += OutputConstraint;
+ ReadOnly = ReadNone = false;
}
if (Info.isReadWrite()) {
@@ -1953,6 +1962,9 @@
TargetInfo::ConstraintInfo &Info = InputConstraintInfos[i];
+ if (Info.allowsMemory())
+ ReadNone = false;
+
if (!Constraints.empty())
Constraints += ',';
@@ -2017,7 +2029,9 @@
for (unsigned i = 0, e = S.getNumClobbers(); i != e; i++) {
StringRef Clobber = S.getClobber(i);
- if (Clobber != "memory" && Clobber != "cc")
+ if (Clobber == "memory")
+ ReadOnly = ReadNone = false;
+ else if (Clobber != "cc")
Clobber = getTarget().getNormalizedGCCRegisterName(Clobber);
if (!Constraints.empty())
@@ -2057,6 +2071,16 @@
Result->addAttribute(llvm::AttributeSet::FunctionIndex,
llvm::Attribute::NoUnwind);
+ // Attach readnone and readonly attributes.
+ if (!HasSideEffect) {
+ if (ReadNone)
+ Result->addAttribute(llvm::AttributeSet::FunctionIndex,
+ llvm::Attribute::ReadNone);
+ else if (ReadOnly)
+ Result->addAttribute(llvm::AttributeSet::FunctionIndex,
+ llvm::Attribute::ReadOnly);
+ }
+
// Slap the source location of the inline asm into a !srcloc metadata on the
// call.
if (const GCCAsmStmt *gccAsmStmt = dyn_cast<GCCAsmStmt>(&S)) {
Index: test/CodeGen/asm-attrs.c
===================================================================
--- /dev/null
+++ test/CodeGen/asm-attrs.c
@@ -0,0 +1,33 @@
+// RUN: %clang_cc1 -triple armv7-apple-darwin -emit-llvm %s -o - | FileCheck %s
+
+// CHECK: call i32 asm "foo0", {{.*}} [[READNONE:#[0-9]+]]
+// CHECK: call i32 asm "foo1", {{.*}} [[READNONE]]
+// CHECK: call i32 asm "foo2", {{.*}} [[NOATTRS:#[0-9]+]]
+// CHECK: call i32 asm sideeffect "foo3", {{.*}} [[NOATTRS]]
+// CHECK: call i32 asm "foo4", {{.*}} [[READONLY:#[0-9]+]]
+// CHECK: call i32 asm "foo5", {{.*}} [[READONLY]]
+// CHECK: call i32 asm "foo6", {{.*}} [[NOATTRS]]
+// CHECK: call void asm sideeffect "foo7", {{.*}} [[NOATTRS]]
+// CHECK: call void asm "foo8", {{.*}} [[NOATTRS]]
+
+// CHECK: attributes [[READNONE]] = { nounwind readnone }
+// CHECK: attributes [[NOATTRS]] = { nounwind }
+// CHECK: attributes [[READONLY]] = { nounwind readonly }
+
+int g0, g1;
+
+struct S {
+ int i;
+} g2;
+
+void test_attrs(int a) {
+ __asm__ ("foo0" : "=r"(g1) : "r"(a));
+ __asm__ ("foo1" : "=r"(g1) : "r"(a) : "cc");
+ __asm__ ("foo2" : "=r"(g1) : "r"(a) : "memory");
+ __asm__ volatile("foo3" : "=r"(g1) : "r"(a));
+ __asm__ ("foo4" : "=r"(g1) : "r"(a), "m"(g0));
+ __asm__ ("foo5" : "=r"(g1) : "r"(a), "Q"(g0));
+ __asm__ ("foo6" : "=r"(g1), "=m"(g0) : "r"(a));
+ __asm__ ("foo7" : : "r"(a));
+ __asm__ ("foo8" : "=r"(g2) : "r"(a));
+}
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