[clang] f4bbcac - [Clang] Allow the value of unroll count to be zero in `#pragma GCC unroll` and `#pragma unroll` (#88666)
via cfe-commits
cfe-commits at lists.llvm.org
Thu Apr 18 20:52:04 PDT 2024
Author: yronglin
Date: 2024-04-19T11:51:59+08:00
New Revision: f4bbcac244eded55acf02cc9fd74eb3f0b075304
URL: https://github.com/llvm/llvm-project/commit/f4bbcac244eded55acf02cc9fd74eb3f0b075304
DIFF: https://github.com/llvm/llvm-project/commit/f4bbcac244eded55acf02cc9fd74eb3f0b075304.diff
LOG: [Clang] Allow the value of unroll count to be zero in `#pragma GCC unroll` and `#pragma unroll` (#88666)
Fixes https://github.com/llvm/llvm-project/issues/88624
GCC allows the value of loop unroll count to be zero, and the values of
0 and 1 block any unrolling of the loop. This PR aims to make clang
keeps the same behavior with GCC.
https://gcc.gnu.org/onlinedocs/gcc/Loop-Specific-Pragmas.html
---------
Signed-off-by: yronglin <yronglin777 at gmail.com>
Added:
Modified:
clang/docs/ReleaseNotes.rst
clang/include/clang/Sema/Sema.h
clang/lib/CodeGen/CGLoopInfo.cpp
clang/lib/Parse/ParsePragma.cpp
clang/lib/Sema/SemaExpr.cpp
clang/lib/Sema/SemaStmtAttr.cpp
clang/lib/Sema/SemaTemplateInstantiate.cpp
clang/test/CodeGenCXX/pragma-gcc-unroll.cpp
clang/test/Parser/pragma-unroll.cpp
Removed:
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 205c6e573d567c..193bbd6b1a4702 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -431,6 +431,10 @@ Bug Fixes in This Version
during instantiation, and instead will only diagnose it once, during checking
of the function template.
+- Clang now allows the value of unroll count to be zero in ``#pragma GCC unroll`` and ``#pragma unroll``.
+ The values of 0 and 1 block any unrolling of the loop. This keeps the same behavior with GCC.
+ Fixes (`#88624 <https://github.com/llvm/llvm-project/issues/88624>`_).
+
Bug Fixes to Compiler Builtins
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 1e89dfc58d92b1..ffc58c681cdcd5 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -5445,7 +5445,7 @@ class Sema final : public SemaBase {
ExprResult ActOnPredefinedExpr(SourceLocation Loc, tok::TokenKind Kind);
ExprResult ActOnIntegerConstant(SourceLocation Loc, uint64_t Val);
- bool CheckLoopHintExpr(Expr *E, SourceLocation Loc);
+ bool CheckLoopHintExpr(Expr *E, SourceLocation Loc, bool AllowZero);
ExprResult ActOnNumericConstant(const Token &Tok, Scope *UDLScope = nullptr);
ExprResult ActOnCharacterConstant(const Token &Tok,
diff --git a/clang/lib/CodeGen/CGLoopInfo.cpp b/clang/lib/CodeGen/CGLoopInfo.cpp
index 0d4800b90a2f26..72d1471021ac02 100644
--- a/clang/lib/CodeGen/CGLoopInfo.cpp
+++ b/clang/lib/CodeGen/CGLoopInfo.cpp
@@ -673,6 +673,8 @@ void LoopInfoStack::push(BasicBlock *Header, clang::ASTContext &Ctx,
setPipelineDisabled(true);
break;
case LoopHintAttr::UnrollCount:
+ setUnrollState(LoopAttributes::Disable);
+ break;
case LoopHintAttr::UnrollAndJamCount:
case LoopHintAttr::VectorizeWidth:
case LoopHintAttr::InterleaveCount:
diff --git a/clang/lib/Parse/ParsePragma.cpp b/clang/lib/Parse/ParsePragma.cpp
index 3979f75b6020db..cd0fab5fe31d3f 100644
--- a/clang/lib/Parse/ParsePragma.cpp
+++ b/clang/lib/Parse/ParsePragma.cpp
@@ -1569,7 +1569,8 @@ bool Parser::HandlePragmaLoopHint(LoopHint &Hint) {
ConsumeToken(); // Consume the constant expression eof terminator.
if (Arg2Error || R.isInvalid() ||
- Actions.CheckLoopHintExpr(R.get(), Toks[0].getLocation()))
+ Actions.CheckLoopHintExpr(R.get(), Toks[0].getLocation(),
+ /*AllowZero=*/false))
return false;
// Argument is a constant expression with an integer type.
@@ -1594,7 +1595,8 @@ bool Parser::HandlePragmaLoopHint(LoopHint &Hint) {
ConsumeToken(); // Consume the constant expression eof terminator.
if (R.isInvalid() ||
- Actions.CheckLoopHintExpr(R.get(), Toks[0].getLocation()))
+ Actions.CheckLoopHintExpr(R.get(), Toks[0].getLocation(),
+ /*AllowZero=*/true))
return false;
// Argument is a constant expression with an integer type.
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index c7e1d1daafea99..2c444d3f8dc484 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -3902,7 +3902,7 @@ static Expr *BuildFloatingLiteral(Sema &S, NumericLiteralParser &Literal,
return FloatingLiteral::Create(S.Context, Val, isExact, Ty, Loc);
}
-bool Sema::CheckLoopHintExpr(Expr *E, SourceLocation Loc) {
+bool Sema::CheckLoopHintExpr(Expr *E, SourceLocation Loc, bool AllowZero) {
assert(E && "Invalid expression");
if (E->isValueDependent())
@@ -3920,7 +3920,13 @@ bool Sema::CheckLoopHintExpr(Expr *E, SourceLocation Loc) {
if (R.isInvalid())
return true;
- bool ValueIsPositive = ValueAPS.isStrictlyPositive();
+ // GCC allows the value of unroll count to be 0.
+ // https://gcc.gnu.org/onlinedocs/gcc/Loop-Specific-Pragmas.html says
+ // "The values of 0 and 1 block any unrolling of the loop."
+ // The values doesn't have to be strictly positive in '#pragma GCC unroll' and
+ // '#pragma unroll' cases.
+ bool ValueIsPositive =
+ AllowZero ? ValueAPS.isNonNegative() : ValueAPS.isStrictlyPositive();
if (!ValueIsPositive || ValueAPS.getActiveBits() > 31) {
Diag(E->getExprLoc(), diag::err_pragma_loop_invalid_argument_value)
<< toString(ValueAPS, 10) << ValueIsPositive;
diff --git a/clang/lib/Sema/SemaStmtAttr.cpp b/clang/lib/Sema/SemaStmtAttr.cpp
index a0339273a0ba35..fbeffda95cee76 100644
--- a/clang/lib/Sema/SemaStmtAttr.cpp
+++ b/clang/lib/Sema/SemaStmtAttr.cpp
@@ -109,9 +109,17 @@ static Attr *handleLoopHintAttr(Sema &S, Stmt *St, const ParsedAttr &A,
SetHints(LoopHintAttr::Unroll, LoopHintAttr::Disable);
} else if (PragmaName == "unroll") {
// #pragma unroll N
- if (ValueExpr)
- SetHints(LoopHintAttr::UnrollCount, LoopHintAttr::Numeric);
- else
+ if (ValueExpr) {
+ llvm::APSInt ValueAPS;
+ ExprResult R = S.VerifyIntegerConstantExpression(ValueExpr, &ValueAPS);
+ assert(!R.isInvalid() && "unroll count value must be a valid value, it's "
+ "should be checked in Sema::CheckLoopHintExpr");
+ // The values of 0 and 1 block any unrolling of the loop.
+ if (ValueAPS.isZero() || ValueAPS.isOne())
+ SetHints(LoopHintAttr::UnrollCount, LoopHintAttr::Disable);
+ else
+ SetHints(LoopHintAttr::UnrollCount, LoopHintAttr::Numeric);
+ } else
SetHints(LoopHintAttr::Unroll, LoopHintAttr::Enable);
} else if (PragmaName == "nounroll_and_jam") {
SetHints(LoopHintAttr::UnrollAndJam, LoopHintAttr::Disable);
@@ -142,7 +150,8 @@ static Attr *handleLoopHintAttr(Sema &S, Stmt *St, const ParsedAttr &A,
if (Option == LoopHintAttr::VectorizeWidth) {
assert((ValueExpr || (StateLoc && StateLoc->Ident)) &&
"Attribute must have a valid value expression or argument.");
- if (ValueExpr && S.CheckLoopHintExpr(ValueExpr, St->getBeginLoc()))
+ if (ValueExpr && S.CheckLoopHintExpr(ValueExpr, St->getBeginLoc(),
+ /*AllowZero=*/false))
return nullptr;
if (StateLoc && StateLoc->Ident && StateLoc->Ident->isStr("scalable"))
State = LoopHintAttr::ScalableWidth;
@@ -152,7 +161,8 @@ static Attr *handleLoopHintAttr(Sema &S, Stmt *St, const ParsedAttr &A,
Option == LoopHintAttr::UnrollCount ||
Option == LoopHintAttr::PipelineInitiationInterval) {
assert(ValueExpr && "Attribute must have a valid value expression.");
- if (S.CheckLoopHintExpr(ValueExpr, St->getBeginLoc()))
+ if (S.CheckLoopHintExpr(ValueExpr, St->getBeginLoc(),
+ /*AllowZero=*/false))
return nullptr;
State = LoopHintAttr::Numeric;
} else if (Option == LoopHintAttr::Vectorize ||
diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
index 7cd428de0bb32d..3e6676f21c9be0 100644
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -2150,7 +2150,8 @@ TemplateInstantiator::TransformLoopHintAttr(const LoopHintAttr *LH) {
return LH;
// Generate error if there is a problem with the value.
- if (getSema().CheckLoopHintExpr(TransformedExpr, LH->getLocation()))
+ if (getSema().CheckLoopHintExpr(TransformedExpr, LH->getLocation(),
+ LH->getOption() == LoopHintAttr::UnrollCount))
return LH;
// Create new LoopHintValueAttr with integral expression in place of the
diff --git a/clang/test/CodeGenCXX/pragma-gcc-unroll.cpp b/clang/test/CodeGenCXX/pragma-gcc-unroll.cpp
index ed75e0b6e3c364..8a94a5cc91e239 100644
--- a/clang/test/CodeGenCXX/pragma-gcc-unroll.cpp
+++ b/clang/test/CodeGenCXX/pragma-gcc-unroll.cpp
@@ -96,6 +96,26 @@ void template_test(double *List, int Length) {
for_template_define_test<double>(List, Length, Value);
}
+void for_unroll_zero_test(int *List, int Length) {
+ // CHECK: define {{.*}} @_Z20for_unroll_zero_testPii
+ #pragma GCC unroll 0
+ for (int i = 0; i < Length; i++) {
+ // CHECK: br label {{.*}}, !llvm.loop ![[LOOP_14:.*]]
+ List[i] = i * 2;
+ }
+}
+
+void while_unroll_zero_test(int *List, int Length) {
+ // CHECK: define {{.*}} @_Z22while_unroll_zero_testPii
+ int i = 0;
+#pragma GCC unroll(0)
+ while (i < Length) {
+ // CHECK: br label {{.*}}, !llvm.loop ![[LOOP_15:.*]]
+ List[i] = i * 2;
+ i++;
+ }
+}
+
// CHECK: ![[LOOP_1]] = distinct !{![[LOOP_1]], [[MP:![0-9]+]], ![[UNROLL_ENABLE:.*]]}
// CHECK: ![[UNROLL_ENABLE]] = !{!"llvm.loop.unroll.enable"}
// CHECK: ![[LOOP_2]] = distinct !{![[LOOP_2:.*]], ![[UNROLL_DISABLE:.*]]}
@@ -107,3 +127,5 @@ void template_test(double *List, int Length) {
// CHECK: ![[LOOP_5]] = distinct !{![[LOOP_5]], ![[UNROLL_8:.*]]}
// CHECK: ![[LOOP_6]] = distinct !{![[LOOP_6]], ![[UNROLL_8:.*]]}
// CHECK: ![[LOOP_7]] = distinct !{![[LOOP_7]], ![[UNROLL_8:.*]]}
+// CHECK: ![[LOOP_14]] = distinct !{![[LOOP_14]], [[MP]], ![[UNROLL_DISABLE:.*]]}
+// CHECK: ![[LOOP_15]] = distinct !{![[LOOP_15]], [[MP]], ![[UNROLL_DISABLE:.*]]}
diff --git a/clang/test/Parser/pragma-unroll.cpp b/clang/test/Parser/pragma-unroll.cpp
index c89cf49a002065..f41bd7a18d5a41 100644
--- a/clang/test/Parser/pragma-unroll.cpp
+++ b/clang/test/Parser/pragma-unroll.cpp
@@ -40,14 +40,18 @@ void test(int *List, int Length) {
/* expected-error {{expected ')'}} */ #pragma unroll(()
/* expected-error {{expected expression}} */ #pragma unroll -
-/* expected-error {{invalid value '0'; must be positive}} */ #pragma unroll(0)
-/* expected-error {{invalid value '0'; must be positive}} */ #pragma unroll 0
+/* The values of 0 and 1 block any unrolling of the loop. */ #pragma unroll 0
/* expected-error {{value '3000000000' is too large}} */ #pragma unroll(3000000000)
/* expected-error {{value '3000000000' is too large}} */ #pragma unroll 3000000000
while (i-8 < Length) {
List[i] = i;
}
+/* The values of 0 and 1 block any unrolling of the loop. */ #pragma unroll(0)
+ while (i-8 < Length) {
+ List[i] = i;
+ }
+
#pragma unroll
/* expected-error {{expected a for, while, or do-while loop to follow '#pragma unroll'}} */ int j = Length;
#pragma unroll 4
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