[llvm] 169ae6d - [APInt] Allow extending and truncating to the same width
Jay Foad via llvm-commits
llvm-commits at lists.llvm.org
Sat May 14 02:03:49 PDT 2022
Author: Jay Foad
Date: 2022-05-14T09:54:24+01:00
New Revision: 169ae6db69882605a69e184237640f0c557243ee
URL: https://github.com/llvm/llvm-project/commit/169ae6db69882605a69e184237640f0c557243ee
DIFF: https://github.com/llvm/llvm-project/commit/169ae6db69882605a69e184237640f0c557243ee.diff
LOG: [APInt] Allow extending and truncating to the same width
Allow zext, sext, trunc, truncUSat and truncSSat to extend or truncate
to the same bit width, which is a no-op.
Disallowing this forced clients to use workarounds like using
zextOrTrunc (even though they never wanted truncation) or zextOrSelf
(even though they did not want its strange behaviour of allowing a
*smaller* bit width, which is also treated as a no-op).
Differential Revision: https://reviews.llvm.org/D125556
Added:
Modified:
llvm/include/llvm/ADT/APInt.h
llvm/lib/Support/APInt.cpp
llvm/unittests/ADT/APIntTest.cpp
Removed:
################################################################################
diff --git a/llvm/include/llvm/ADT/APInt.h b/llvm/include/llvm/ADT/APInt.h
index c364679aa457a..3c75417872f5b 100644
--- a/llvm/include/llvm/ADT/APInt.h
+++ b/llvm/include/llvm/ADT/APInt.h
@@ -1218,7 +1218,7 @@ class LLVM_NODISCARD APInt {
/// Truncate to new width.
///
/// Truncate the APInt to a specified width. It is an error to specify a width
- /// that is greater than or equal to the current width.
+ /// that is greater than the current width.
APInt trunc(unsigned width) const;
/// Truncate to new width with unsigned saturation.
@@ -1238,7 +1238,7 @@ class LLVM_NODISCARD APInt {
///
/// This operation sign extends the APInt to a new width. If the high order
/// bit is set, the fill on the left will be done with 1 bits, otherwise zero.
- /// It is an error to specify a width that is less than or equal to the
+ /// It is an error to specify a width that is less than the
/// current width.
APInt sext(unsigned width) const;
@@ -1246,7 +1246,7 @@ class LLVM_NODISCARD APInt {
///
/// This operation zero extends the APInt to a new width. The high order bits
/// are filled with 0 bits. It is an error to specify a width that is less
- /// than or equal to the current width.
+ /// than the current width.
APInt zext(unsigned width) const;
/// Sign extend or truncate to width
diff --git a/llvm/lib/Support/APInt.cpp b/llvm/lib/Support/APInt.cpp
index 401b4f7a76206..3fc0415790ec7 100644
--- a/llvm/lib/Support/APInt.cpp
+++ b/llvm/lib/Support/APInt.cpp
@@ -896,11 +896,14 @@ double APInt::roundToDouble(bool isSigned) const {
// Truncate to new width.
APInt APInt::trunc(unsigned width) const {
- assert(width < BitWidth && "Invalid APInt Truncate request");
+ assert(width <= BitWidth && "Invalid APInt Truncate request");
if (width <= APINT_BITS_PER_WORD)
return APInt(width, getRawData()[0]);
+ if (width == BitWidth)
+ return *this;
+
APInt Result(getMemory(getNumWords(width)), width);
// Copy full words.
@@ -918,7 +921,7 @@ APInt APInt::trunc(unsigned width) const {
// Truncate to new width with unsigned saturation.
APInt APInt::truncUSat(unsigned width) const {
- assert(width < BitWidth && "Invalid APInt Truncate request");
+ assert(width <= BitWidth && "Invalid APInt Truncate request");
// Can we just losslessly truncate it?
if (isIntN(width))
@@ -929,7 +932,7 @@ APInt APInt::truncUSat(unsigned width) const {
// Truncate to new width with signed saturation.
APInt APInt::truncSSat(unsigned width) const {
- assert(width < BitWidth && "Invalid APInt Truncate request");
+ assert(width <= BitWidth && "Invalid APInt Truncate request");
// Can we just losslessly truncate it?
if (isSignedIntN(width))
@@ -941,11 +944,14 @@ APInt APInt::truncSSat(unsigned width) const {
// Sign extend to a new width.
APInt APInt::sext(unsigned Width) const {
- assert(Width > BitWidth && "Invalid APInt SignExtend request");
+ assert(Width >= BitWidth && "Invalid APInt SignExtend request");
if (Width <= APINT_BITS_PER_WORD)
return APInt(Width, SignExtend64(U.VAL, BitWidth));
+ if (Width == BitWidth)
+ return *this;
+
APInt Result(getMemory(getNumWords(Width)), Width);
// Copy words.
@@ -965,11 +971,14 @@ APInt APInt::sext(unsigned Width) const {
// Zero extend to a new width.
APInt APInt::zext(unsigned width) const {
- assert(width > BitWidth && "Invalid APInt ZeroExtend request");
+ assert(width >= BitWidth && "Invalid APInt ZeroExtend request");
if (width <= APINT_BITS_PER_WORD)
return APInt(width, U.VAL);
+ if (width == BitWidth)
+ return *this;
+
APInt Result(getMemory(getNumWords(width)), width);
// Copy words.
diff --git a/llvm/unittests/ADT/APIntTest.cpp b/llvm/unittests/ADT/APIntTest.cpp
index ec3d5f82337f2..aca4a9ade8ff6 100644
--- a/llvm/unittests/ADT/APIntTest.cpp
+++ b/llvm/unittests/ADT/APIntTest.cpp
@@ -1181,18 +1181,22 @@ TEST(APIntTest, SaturatingMath) {
APInt AP_100 = APInt(8, 100);
APInt AP_200 = APInt(8, 200);
+ EXPECT_EQ(APInt(8, 100), AP_100.truncUSat(8));
EXPECT_EQ(APInt(7, 100), AP_100.truncUSat(7));
EXPECT_EQ(APInt(6, 63), AP_100.truncUSat(6));
EXPECT_EQ(APInt(5, 31), AP_100.truncUSat(5));
+ EXPECT_EQ(APInt(8, 200), AP_200.truncUSat(8));
EXPECT_EQ(APInt(7, 127), AP_200.truncUSat(7));
EXPECT_EQ(APInt(6, 63), AP_200.truncUSat(6));
EXPECT_EQ(APInt(5, 31), AP_200.truncUSat(5));
+ EXPECT_EQ(APInt(8, 42), AP_42.truncSSat(8));
EXPECT_EQ(APInt(7, 42), AP_42.truncSSat(7));
EXPECT_EQ(APInt(6, 31), AP_42.truncSSat(6));
EXPECT_EQ(APInt(5, 15), AP_42.truncSSat(5));
+ EXPECT_EQ(APInt(8, -56), AP_200.truncSSat(8));
EXPECT_EQ(APInt(7, -56), AP_200.truncSSat(7));
EXPECT_EQ(APInt(6, -32), AP_200.truncSSat(6));
EXPECT_EQ(APInt(5, -16), AP_200.truncSSat(5));
@@ -2637,23 +2641,28 @@ TEST(APIntTest, sext) {
EXPECT_EQ(~uint64_t(0), APInt(1, 1).sext(64));
APInt i32_max(APInt::getSignedMaxValue(32).sext(63));
+ EXPECT_EQ(i32_max, i32_max.sext(63));
EXPECT_EQ(32U, i32_max.countLeadingZeros());
EXPECT_EQ(0U, i32_max.countTrailingZeros());
EXPECT_EQ(31U, i32_max.countPopulation());
APInt i32_min(APInt::getSignedMinValue(32).sext(63));
+ EXPECT_EQ(i32_min, i32_min.sext(63));
EXPECT_EQ(32U, i32_min.countLeadingOnes());
EXPECT_EQ(31U, i32_min.countTrailingZeros());
EXPECT_EQ(32U, i32_min.countPopulation());
APInt i32_neg1(APInt(32, ~uint64_t(0)).sext(63));
+ EXPECT_EQ(i32_neg1, i32_neg1.sext(63));
EXPECT_EQ(63U, i32_neg1.countLeadingOnes());
EXPECT_EQ(0U, i32_neg1.countTrailingZeros());
EXPECT_EQ(63U, i32_neg1.countPopulation());
}
-TEST(APIntTest, truncOrSelf) {
+TEST(APIntTest, trunc) {
APInt val(32, 0xFFFFFFFF);
+ EXPECT_EQ(0xFFFF, val.trunc(16));
+ EXPECT_EQ(0xFFFFFFFF, val.trunc(32));
EXPECT_EQ(0xFFFF, val.truncOrSelf(16));
EXPECT_EQ(0xFFFFFFFF, val.truncOrSelf(32));
EXPECT_EQ(0xFFFFFFFF, val.truncOrSelf(64));
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