[clang] 2fd180b - [IR] Reduce max supported integer from 2^24-1 to 2^23.
Craig Topper via cfe-commits
cfe-commits at lists.llvm.org
Tue Sep 14 08:11:57 PDT 2021
Author: Craig Topper
Date: 2021-09-14T07:52:10-07:00
New Revision: 2fd180bbb9a7bb8604a5aca31f1ca9dc5358a433
URL: https://github.com/llvm/llvm-project/commit/2fd180bbb9a7bb8604a5aca31f1ca9dc5358a433
DIFF: https://github.com/llvm/llvm-project/commit/2fd180bbb9a7bb8604a5aca31f1ca9dc5358a433.diff
LOG: [IR] Reduce max supported integer from 2^24-1 to 2^23.
SelectionDAG will promote illegal types up to a power of 2 before
splitting down to a legal type. This will create an IntegerType
with a bit width that must be <= MAX_INT_BITS. This places an
effective upper limit on any type of 2^23 so that we don't try
create a 2^24 type.
I considered putting a fatal error somewhere in the path from
TargetLowering::getTypeConversion down to IntegerType::get, but
limiting the type in IR seemed better.
This breaks backwards compatibility with IR that is using a really
large type. I suspect such IR is going to be very rare due to the
the compile time costs such a type likely incurs.
Prevents the ICE in PR51829.
Reviewed By: efriedma, aaron.ballman
Differential Revision: https://reviews.llvm.org/D109721
Added:
Modified:
clang/docs/ReleaseNotes.rst
clang/test/CodeGen/ext-int.c
clang/test/CodeGenCXX/ext-int.cpp
clang/test/SemaCXX/ext-int.cpp
llvm/docs/LangRef.rst
llvm/docs/ReleaseNotes.rst
llvm/include/llvm/IR/DerivedTypes.h
llvm/test/Assembler/invalid-inttype.ll
llvm/test/Assembler/max-inttype.ll
Removed:
################################################################################
diff --git a/clang/docs/ReleaseNotes.rst b/clang/docs/ReleaseNotes.rst
index 56f91b4e5877f..4c2bf04e9a09e 100644
--- a/clang/docs/ReleaseNotes.rst
+++ b/clang/docs/ReleaseNotes.rst
@@ -56,7 +56,8 @@ Improvements to Clang's diagnostics
Non-comprehensive list of changes in this release
-------------------------------------------------
-- ...
+- Maximum _ExtInt size was decreased from 16,777,215 bits to 8,388,608 bits.
+ Motivation for this was discussed in PR51829.
New Compiler Flags
------------------
diff --git a/clang/test/CodeGen/ext-int.c b/clang/test/CodeGen/ext-int.c
index d8e763283bfd9..44ac45b425ac2 100644
--- a/clang/test/CodeGen/ext-int.c
+++ b/clang/test/CodeGen/ext-int.c
@@ -28,7 +28,7 @@ void VLATest(_ExtInt(3) A, _ExtInt(99) B, _ExtInt(123456) C) {
struct S {
_ExtInt(17) A;
- _ExtInt(16777200) B;
+ _ExtInt(8388600) B;
_ExtInt(17) C;
};
@@ -41,9 +41,9 @@ void OffsetOfTest() {
// LIN32: store i32 4, i32* %{{.+}}
// WINCHECK32: store i32 8, i32* %{{.+}}
int C = __builtin_offsetof(struct S,C);
- // CHECK64: store i32 2097160, i32* %{{.+}}
- // LIN32: store i32 2097156, i32* %{{.+}}
- // WIN32: store i32 2097160, i32* %{{.+}}
+ // CHECK64: store i32 1048584, i32* %{{.+}}
+ // LIN32: store i32 1048580, i32* %{{.+}}
+ // WIN32: store i32 1048584, i32* %{{.+}}
}
void Size1ExtIntParam(unsigned _ExtInt(1) A) {
diff --git a/clang/test/CodeGenCXX/ext-int.cpp b/clang/test/CodeGenCXX/ext-int.cpp
index 7f3bc07e98dd4..3cbcf1331eaff 100644
--- a/clang/test/CodeGenCXX/ext-int.cpp
+++ b/clang/test/CodeGenCXX/ext-int.cpp
@@ -223,23 +223,23 @@ void TakesVarargs(int i, ...) {
// WIN: %[[LOADV4:.+]] = load i129, i129* %[[LOADP4]]
// WIN: store i129 %[[LOADV4]], i129*
- _ExtInt(16777200) E = __builtin_va_arg(args, _ExtInt(16777200));
+ _ExtInt(8388600) E = __builtin_va_arg(args, _ExtInt(8388600));
// LIN: %[[AD5:.+]] = getelementptr inbounds [1 x %struct.__va_list_tag], [1 x %struct.__va_list_tag]* %[[ARGS]]
// LIN: %[[OFA_P5:.+]] = getelementptr inbounds %struct.__va_list_tag, %struct.__va_list_tag* %[[AD5]], i32 0, i32 2
// LIN: %[[OFA5:.+]] = load i8*, i8** %[[OFA_P5]]
- // LIN: %[[BC5:.+]] = bitcast i8* %[[OFA5]] to i16777200*
- // LIN: %[[OFANEXT5:.+]] = getelementptr i8, i8* %[[OFA5]], i32 2097152
+ // LIN: %[[BC5:.+]] = bitcast i8* %[[OFA5]] to i8388600*
+ // LIN: %[[OFANEXT5:.+]] = getelementptr i8, i8* %[[OFA5]], i32 1048576
// LIN: store i8* %[[OFANEXT5]], i8** %[[OFA_P5]]
- // LIN: %[[LOAD5:.+]] = load i16777200, i16777200* %[[BC5]]
- // LIN: store i16777200 %[[LOAD5]], i16777200*
+ // LIN: %[[LOAD5:.+]] = load i8388600, i8388600* %[[BC5]]
+ // LIN: store i8388600 %[[LOAD5]], i8388600*
// WIN: %[[CUR5:.+]] = load i8*, i8** %[[ARGS]]
// WIN: %[[NEXT5:.+]] = getelementptr inbounds i8, i8* %[[CUR5]], i64 8
// WIN: store i8* %[[NEXT5]], i8** %[[ARGS]]
- // WIN: %[[BC5:.+]] = bitcast i8* %[[CUR5]] to i16777200**
- // WIN: %[[LOADP5:.+]] = load i16777200*, i16777200** %[[BC5]]
- // WIN: %[[LOADV5:.+]] = load i16777200, i16777200* %[[LOADP5]]
- // WIN: store i16777200 %[[LOADV5]], i16777200*
+ // WIN: %[[BC5:.+]] = bitcast i8* %[[CUR5]] to i8388600**
+ // WIN: %[[LOADP5:.+]] = load i8388600*, i8388600** %[[BC5]]
+ // WIN: %[[LOADV5:.+]] = load i8388600, i8388600* %[[LOADP5]]
+ // WIN: store i8388600 %[[LOADV5]], i8388600*
__builtin_va_end(args);
// LIN: %[[ENDAD:.+]] = getelementptr inbounds [1 x %struct.__va_list_tag], [1 x %struct.__va_list_tag]* %[[ARGS]]
@@ -295,7 +295,7 @@ void ExplicitCasts() {
struct S {
_ExtInt(17) A;
- _ExtInt(16777200) B;
+ _ExtInt(8388600) B;
_ExtInt(17) C;
};
@@ -308,7 +308,7 @@ void OffsetOfTest() {
auto B = __builtin_offsetof(S,B);
// CHECK: store i64 8, i64* %{{.+}}
auto C = __builtin_offsetof(S,C);
- // CHECK: store i64 2097160, i64* %{{.+}}
+ // CHECK: store i64 1048584, i64* %{{.+}}
}
diff --git a/clang/test/SemaCXX/ext-int.cpp b/clang/test/SemaCXX/ext-int.cpp
index a3e8dd82fc5da..b3bcd197a6e28 100644
--- a/clang/test/SemaCXX/ext-int.cpp
+++ b/clang/test/SemaCXX/ext-int.cpp
@@ -29,8 +29,8 @@ _ExtInt(33) Declarations(_ExtInt(48) &Param) { // Useable in params and returns.
constexpr _ExtInt(7) o = 33;
// Check LLVM imposed max size.
- _ExtInt(0xFFFFFFFFFF) p; // expected-error {{signed _ExtInt of bit sizes greater than 16777215 not supported}}
- unsigned _ExtInt(0xFFFFFFFFFF) q; // expected-error {{unsigned _ExtInt of bit sizes greater than 16777215 not supported}}
+ _ExtInt(8388609) p; // expected-error {{signed _ExtInt of bit sizes greater than 8388608 not supported}}
+ unsigned _ExtInt(0xFFFFFFFFFF) q; // expected-error {{unsigned _ExtInt of bit sizes greater than 8388608 not supported}}
// Ensure template params are instantiated correctly.
// expected-error at 5{{signed _ExtInt must have a bit size of at least 2}}
diff --git a/llvm/docs/LangRef.rst b/llvm/docs/LangRef.rst
index 3f2821f0d207b..7754cf370b615 100644
--- a/llvm/docs/LangRef.rst
+++ b/llvm/docs/LangRef.rst
@@ -3303,7 +3303,7 @@ Integer Type
The integer type is a very simple type that simply specifies an
arbitrary bit width for the integer type desired. Any bit width from 1
-bit to 2\ :sup:`23`\ -1 (about 8 million) can be specified.
+bit to 2\ :sup:`23`\ (about 8 million) can be specified.
:Syntax:
diff --git a/llvm/docs/ReleaseNotes.rst b/llvm/docs/ReleaseNotes.rst
index 6408f63ef4a7c..fa0adbbeb6a1e 100644
--- a/llvm/docs/ReleaseNotes.rst
+++ b/llvm/docs/ReleaseNotes.rst
@@ -59,6 +59,7 @@ Changes to the LLVM IR
* Using the legacy pass manager for the optimization pipeline is deprecated and
will be removed after LLVM 14. In the meantime, only minimal effort will be
made to maintain the legacy pass manager for the optimization pipeline.
+* Max allowed integer type was reduced from 2^24-1 bits to 2^23 bits.
Changes to building LLVM
------------------------
diff --git a/llvm/include/llvm/IR/DerivedTypes.h b/llvm/include/llvm/IR/DerivedTypes.h
index b68a912b5f705..8a1b26e699e32 100644
--- a/llvm/include/llvm/IR/DerivedTypes.h
+++ b/llvm/include/llvm/IR/DerivedTypes.h
@@ -49,10 +49,11 @@ class IntegerType : public Type {
/// This enum is just used to hold constants we need for IntegerType.
enum {
MIN_INT_BITS = 1, ///< Minimum number of bits that can be specified
- MAX_INT_BITS = (1<<24)-1 ///< Maximum number of bits that can be specified
+ MAX_INT_BITS = (1<<23) ///< Maximum number of bits that can be specified
///< Note that bit width is stored in the Type classes SubclassData field
- ///< which has 24 bits. This yields a maximum bit width of 16,777,215
- ///< bits.
+ ///< which has 24 bits. SelectionDAG type legalization can require a
+ ///< power of 2 IntegerType, so limit to the largest representable power
+ ///< of 2, 8388608.
};
/// This static method is the primary way of constructing an IntegerType.
diff --git a/llvm/test/Assembler/invalid-inttype.ll b/llvm/test/Assembler/invalid-inttype.ll
index 145153d8f113f..df3175540fe82 100644
--- a/llvm/test/Assembler/invalid-inttype.ll
+++ b/llvm/test/Assembler/invalid-inttype.ll
@@ -1,5 +1,5 @@
; RUN: not llvm-as < %s 2>&1 | FileCheck %s
-; i16777216 is the smallest integer type that can't be represented in LLVM IR
- at i2 = common global i16777216 0, align 4
+; i8388609 is the smallest integer type that can't be represented in LLVM IR
+ at i2 = common global i8388609 0, align 4
; CHECK: expected type
diff --git a/llvm/test/Assembler/max-inttype.ll b/llvm/test/Assembler/max-inttype.ll
index 10eed60f3db71..f4fec69ac23b2 100644
--- a/llvm/test/Assembler/max-inttype.ll
+++ b/llvm/test/Assembler/max-inttype.ll
@@ -1,4 +1,4 @@
; RUN: llvm-as < %s | llvm-dis
-; i16777215 is the maximum integer type represented in LLVM IR
- at i2 = common global i16777215 0, align 4
+; i838608 is the maximum integer type represented in LLVM IR
+ at i2 = common global i838608 0, align 4
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