[PATCH] D69993: [APInt] Add saturating truncation methods
Roman Lebedev via Phabricator via llvm-commits
llvm-commits at lists.llvm.org
Fri Nov 8 06:53:55 PST 2019
This revision was automatically updated to reflect the committed changes.
Closed by commit rG9ca363d89c10: [APInt] Add saturating truncation methods (authored by lebedev.ri).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D69993/new/
https://reviews.llvm.org/D69993
Files:
llvm/include/llvm/ADT/APInt.h
llvm/lib/Support/APInt.cpp
llvm/unittests/ADT/APIntTest.cpp
Index: llvm/unittests/ADT/APIntTest.cpp
===================================================================
--- llvm/unittests/ADT/APIntTest.cpp
+++ llvm/unittests/ADT/APIntTest.cpp
@@ -1177,9 +1177,26 @@
TEST(APIntTest, SaturatingMath) {
APInt AP_10 = APInt(8, 10);
+ APInt AP_42 = APInt(8, 42);
APInt AP_100 = APInt(8, 100);
APInt AP_200 = APInt(8, 200);
+ 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(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(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(7, -56), AP_200.truncSSat(7));
+ EXPECT_EQ(APInt(6, -32), AP_200.truncSSat(6));
+ EXPECT_EQ(APInt(5, -16), AP_200.truncSSat(5));
+
EXPECT_EQ(APInt(8, 200), AP_100.uadd_sat(AP_100));
EXPECT_EQ(APInt(8, 255), AP_100.uadd_sat(AP_200));
EXPECT_EQ(APInt(8, 255), APInt(8, 255).uadd_sat(APInt(8, 255)));
Index: llvm/lib/Support/APInt.cpp
===================================================================
--- llvm/lib/Support/APInt.cpp
+++ llvm/lib/Support/APInt.cpp
@@ -884,6 +884,31 @@
return Result;
}
+// Truncate to new width with unsigned saturation.
+APInt APInt::truncUSat(unsigned width) const {
+ assert(width < BitWidth && "Invalid APInt Truncate request");
+ assert(width && "Can't truncate to 0 bits");
+
+ // Can we just losslessly truncate it?
+ if (isIntN(width))
+ return trunc(width);
+ // If not, then just return the new limit.
+ return APInt::getMaxValue(width);
+}
+
+// Truncate to new width with signed saturation.
+APInt APInt::truncSSat(unsigned width) const {
+ assert(width < BitWidth && "Invalid APInt Truncate request");
+ assert(width && "Can't truncate to 0 bits");
+
+ // Can we just losslessly truncate it?
+ if (isSignedIntN(width))
+ return trunc(width);
+ // If not, then just return the new limits.
+ return isNegative() ? APInt::getSignedMinValue(width)
+ : APInt::getSignedMaxValue(width);
+}
+
// Sign extend to a new width.
APInt APInt::sext(unsigned Width) const {
assert(Width > BitWidth && "Invalid APInt SignExtend request");
Index: llvm/include/llvm/ADT/APInt.h
===================================================================
--- llvm/include/llvm/ADT/APInt.h
+++ llvm/include/llvm/ADT/APInt.h
@@ -1346,6 +1346,19 @@
/// that is greater than or equal to the current width.
APInt trunc(unsigned width) const;
+ /// Truncate to new width with unsigned saturation.
+ ///
+ /// If the APInt, treated as unsigned integer, can be losslessly truncated to
+ /// the new bitwidth, then return truncated APInt. Else, return max value.
+ APInt truncUSat(unsigned width) const;
+
+ /// Truncate to new width with signed saturation.
+ ///
+ /// If this APInt, treated as signed integer, can be losslessly truncated to
+ /// the new bitwidth, then return truncated APInt. Else, return either
+ /// signed min value if the APInt was negative, or signed max value.
+ APInt truncSSat(unsigned width) const;
+
/// Sign extend to a new width.
///
/// This operation sign extends the APInt to a new width. If the high order
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