[Mlir-commits] [mlir] [mlir][arith] doc updates for ub semantics, and int representations (PR #72932)
Jacob Yu
llvmlistbot at llvm.org
Tue Nov 21 03:27:57 PST 2023
https://github.com/pingshiyu updated https://github.com/llvm/llvm-project/pull/72932
>From b699c27bf79f52c44060bfdf87e3b0c76fc4c29a Mon Sep 17 00:00:00 2001
From: pingshiyu <pingshiyu at gmail.com>
Date: Mon, 20 Nov 2023 21:22:40 +0000
Subject: [PATCH 1/2] [mlir][arith] doc updates for ub semantics, and int
representations
---
.../mlir/Dialect/Arith/IR/ArithBase.td | 6 +-
.../include/mlir/Dialect/Arith/IR/ArithOps.td | 75 ++++++++++++-------
2 files changed, 53 insertions(+), 28 deletions(-)
diff --git a/mlir/include/mlir/Dialect/Arith/IR/ArithBase.td b/mlir/include/mlir/Dialect/Arith/IR/ArithBase.td
index 133af893e4efa74..240e49cfb13d73b 100644
--- a/mlir/include/mlir/Dialect/Arith/IR/ArithBase.td
+++ b/mlir/include/mlir/Dialect/Arith/IR/ArithBase.td
@@ -19,7 +19,11 @@ def Arith_Dialect : Dialect {
The arith dialect is intended to hold basic integer and floating point
mathematical operations. This includes unary, binary, and ternary arithmetic
ops, bitwise and shift ops, cast ops, and compare ops. Operations in this
- dialect also accept vectors and tensors of integers or floats.
+ dialect also accept vectors and tensors of integers or floats. The dialect
+ assumes unsigned integers are represented by bitvectors, and signed integers
+ are represented by bitvectors with a two's complement representation. Unless
+ otherwise stated, the operations within this dialect will propagate poison
+ values (if any of its inputs are poison, then the output is poison).
}];
let hasConstantMaterializer = 1;
diff --git a/mlir/include/mlir/Dialect/Arith/IR/ArithOps.td b/mlir/include/mlir/Dialect/Arith/IR/ArithOps.td
index 58e5385bf3ff268..836606d62554d89 100644
--- a/mlir/include/mlir/Dialect/Arith/IR/ArithOps.td
+++ b/mlir/include/mlir/Dialect/Arith/IR/ArithOps.td
@@ -198,7 +198,9 @@ def Arith_AddIOp : Arith_TotalIntBinaryOp<"addi", [Commutative]> {
The `addi` operation takes two operands and returns one result, each of
these is required to be the same type. This type may be an integer scalar
type, a vector whose element type is integer, or a tensor of integers. It
- has no standard attributes.
+ has no standard attributes. If an overflow occurs, the result is the
+ mathematical value of the addition modulo 2^n, where `n` is the width of
+ the integer type.
Example:
@@ -273,7 +275,11 @@ def Arith_AddUIExtendedOp : Arith_Op<"addui_extended", [Pure, Commutative,
//===----------------------------------------------------------------------===//
def Arith_SubIOp : Arith_TotalIntBinaryOp<"subi"> {
- let summary = "integer subtraction operation";
+ let summary = [{
+ integer subtraction operation. If an overflow occurs, the result is the
+ mathematical value of the addition modulo 2^n, where `n` is the width of
+ the integer type.
+ }];
let hasFolder = 1;
let hasCanonicalizer = 1;
}
@@ -283,7 +289,11 @@ def Arith_SubIOp : Arith_TotalIntBinaryOp<"subi"> {
//===----------------------------------------------------------------------===//
def Arith_MulIOp : Arith_TotalIntBinaryOp<"muli", [Commutative]> {
- let summary = "integer multiplication operation";
+ let summary = [{
+ integer multiplication operation. If an overflow occurs, the result is the
+ mathematical value of the addition modulo 2^n, where `n` is the width of
+ the integer type.
+ }];
let hasFolder = 1;
let hasCanonicalizer = 1;
}
@@ -420,8 +430,8 @@ def Arith_DivSIOp : Arith_IntBinaryOp<"divsi", [ConditionallySpeculatable]> {
Signed integer division. Rounds towards zero. Treats the leading bit as
sign, i.e. `6 / -2 = -3`.
- Note: the semantics of division by zero or signed division overflow (minimum
- value divided by -1) is TBD; do NOT assume any specific behavior.
+ Divison by zero, or signed division overflow (minimum value divided by -1)
+ is undefined behaviour.
Example:
@@ -457,8 +467,7 @@ def Arith_CeilDivUIOp : Arith_IntBinaryOp<"ceildivui",
leading bit as the most significant, i.e. for `i16` given two's complement
representation, `6 / -2 = 6 / (2^16 - 2) = 1`.
- Note: the semantics of division by zero is TBD; do NOT assume any specific
- behavior.
+ Division by zero is undefined behaviour.
Example:
@@ -486,8 +495,8 @@ def Arith_CeilDivSIOp : Arith_IntBinaryOp<"ceildivsi",
let description = [{
Signed integer division. Rounds towards positive infinity, i.e. `7 / -2 = -3`.
- Note: the semantics of division by zero or signed division overflow (minimum
- value divided by -1) is TBD; do NOT assume any specific behavior.
+ Divison by zero, or signed division overflow (minimum value divided by -1)
+ is undefined behaviour.
Example:
@@ -514,8 +523,8 @@ def Arith_FloorDivSIOp : Arith_TotalIntBinaryOp<"floordivsi"> {
let description = [{
Signed integer division. Rounds towards negative infinity, i.e. `5 / -2 = -3`.
- Note: the semantics of division by zero or signed division overflow (minimum
- value divided by -1) is TBD; do NOT assume any specific behavior.
+ Divison by zero, or signed division overflow (minimum value divided by -1)
+ is undefined behaviour.
Example:
@@ -538,8 +547,7 @@ def Arith_RemUIOp : Arith_TotalIntBinaryOp<"remui"> {
Unsigned integer division remainder. Treats the leading bit as the most
significant, i.e. for `i16`, `6 % -2 = 6 % (2^16 - 2) = 6`.
- Note: the semantics of division by zero is TBD; do NOT assume any specific
- behavior.
+ Division by zero is undefined behaviour.
Example:
@@ -567,8 +575,7 @@ def Arith_RemSIOp : Arith_TotalIntBinaryOp<"remsi"> {
Signed integer division remainder. Treats the leading bit as sign, i.e. `6 %
-2 = 0`.
- Note: the semantics of division by zero is TBD; do NOT assume any specific
- behavior.
+ Division by zero is undefined behaviour.
Example:
@@ -680,8 +687,11 @@ def Arith_XOrIOp : Arith_TotalIntBinaryOp<"xori", [Commutative]> {
def Arith_ShLIOp : Arith_TotalIntBinaryOp<"shli"> {
let summary = "integer left-shift";
let description = [{
- The `shli` operation shifts an integer value to the left by a variable
- amount. The low order bits are filled with zeros.
+ The `shli` operation shifts the integer value of the first operand to the left
+ by the integer value of the second operand. The second operand is interpreted as
+ unsigned. The low order bits are filled with zeros. If the value of the second
+ operand is greater than the number of bits in the first operand, then the
+ operation returns a poison.
Example:
@@ -701,9 +711,11 @@ def Arith_ShLIOp : Arith_TotalIntBinaryOp<"shli"> {
def Arith_ShRUIOp : Arith_TotalIntBinaryOp<"shrui"> {
let summary = "unsigned integer right-shift";
let description = [{
- The `shrui` operation shifts an integer value to the right by a variable
- amount. The integer is interpreted as unsigned. The high order bits are
- always filled with zeros.
+ The `shrui` operation shifts an integer value of the first operand to the right
+ by the value of the second operand. The first operand is interpreted as unsigned,
+ and the second operand is interpreted as unsigned. The high order bits are always
+ filled with zeros. If the value of the second operand is greater than the number
+ of bits in the first operand, then the operation returns poison.
Example:
@@ -723,10 +735,13 @@ def Arith_ShRUIOp : Arith_TotalIntBinaryOp<"shrui"> {
def Arith_ShRSIOp : Arith_TotalIntBinaryOp<"shrsi"> {
let summary = "signed integer right-shift";
let description = [{
- The `shrsi` operation shifts an integer value to the right by a variable
- amount. The integer is interpreted as signed. The high order bits in the
- output are filled with copies of the most-significant bit of the shifted
- value (which means that the sign of the value is preserved).
+ The `shrsi` operation shifts an integer value of the first operand to the right
+ by the value of the second operand. The first operand is interpreted as signed,
+ and the second operand is interpreter as unsigned. The high order bits in the
+ output are filled with copies of the most-significant bit of the shifted value
+ (which means that the sign of the value is preserved). If the value of the second
+ operand is greater than the number of bits in the first operand, then the
+ operation returns poison.
Example:
@@ -1422,9 +1437,15 @@ def SelectOp : Arith_Op<"select", [Pure,
let summary = "select operation";
let description = [{
The `arith.select` operation chooses one value based on a binary condition
- supplied as its first operand. If the value of the first operand is `1`,
- the second operand is chosen, otherwise the third operand is chosen.
- The second and the third operand must have the same type.
+ supplied as its first operand.
+
+ If the value of the first operand is `1`, then the second operand is returned,
+ and the third operand is ignored, even if it were poison.
+
+ If the value of the first operand is `0`, then the third operand is returned,
+ and the second operand is ignored, even if it were poison.
+
+ If the value of the first operand is poison, then the operation returns poison.
The operation applies to vectors and tensors elementwise given the _shape_
of all operands is identical. The choice is made for each element
>From a4f22f77a8759f01a5602da7be3cf953147bb930 Mon Sep 17 00:00:00 2001
From: Jacob Yu <pingshiyu at gmail.com>
Date: Tue, 21 Nov 2023 11:27:50 +0000
Subject: [PATCH 2/2] Update mlir/include/mlir/Dialect/Arith/IR/ArithBase.td
Co-authored-by: Jakub Kuderski <kubakuderski at gmail.com>
---
mlir/include/mlir/Dialect/Arith/IR/ArithBase.td | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mlir/include/mlir/Dialect/Arith/IR/ArithBase.td b/mlir/include/mlir/Dialect/Arith/IR/ArithBase.td
index 240e49cfb13d73b..72609112d80472f 100644
--- a/mlir/include/mlir/Dialect/Arith/IR/ArithBase.td
+++ b/mlir/include/mlir/Dialect/Arith/IR/ArithBase.td
@@ -22,8 +22,8 @@ def Arith_Dialect : Dialect {
dialect also accept vectors and tensors of integers or floats. The dialect
assumes unsigned integers are represented by bitvectors, and signed integers
are represented by bitvectors with a two's complement representation. Unless
- otherwise stated, the operations within this dialect will propagate poison
- values (if any of its inputs are poison, then the output is poison).
+ otherwise stated, the operations within this dialect propagate poison
+ values, i.e., if any of its inputs are poison, then the output is poison).
}];
let hasConstantMaterializer = 1;
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