This revision was automatically updated to reflect the committed changes.
Closed by commit rL321771: [CGBuiltin] Handle unsigned mul overflow properly
(PR35750) (authored by vedantk, committed by ).
Changed prior to commit:
https://reviews.llvm.org/D41717?vs=128567&id=128574#toc
Repository:
rL LLVM
https://reviews.llvm.org/D41717
Files:
cfe/trunk/lib/CodeGen/CGBuiltin.cpp
cfe/trunk/test/CodeGen/builtins-overflow.c
Index: cfe/trunk/lib/CodeGen/CGBuiltin.cpp
===================================================================
--- cfe/trunk/lib/CodeGen/CGBuiltin.cpp
+++ cfe/trunk/lib/CodeGen/CGBuiltin.cpp
@@ -915,7 +915,11 @@
Overflow = CGF.Builder.CreateOr(Overflow, TruncOverflow);
}
- Result = CGF.Builder.CreateTrunc(UnsignedResult, ResTy);
+ // Negate the product if it would be negative in infinite precision.
+ Result = CGF.Builder.CreateSelect(
+ IsNegative, CGF.Builder.CreateNeg(UnsignedResult), UnsignedResult);
+
+ Result = CGF.Builder.CreateTrunc(Result, ResTy);
}
assert(Overflow && Result && "Missing overflow or result");
Index: cfe/trunk/test/CodeGen/builtins-overflow.c
===================================================================
--- cfe/trunk/test/CodeGen/builtins-overflow.c
+++ cfe/trunk/test/CodeGen/builtins-overflow.c
@@ -373,7 +373,9 @@
// CHECK-NEXT: [[NotNull:%.*]] = icmp ne i32 [[UnsignedResult]], 0
// CHECK-NEXT: [[Underflow:%.*]] = and i1 [[IsNeg]], [[NotNull]]
// CHECK-NEXT: [[OFlow:%.*]] = or i1 [[UnsignedOFlow]], [[Underflow]]
-// CHECK-NEXT: store i32 [[UnsignedResult]], i32* %{{.*}}, align 4
+// CHECK-NEXT: [[NegatedResult:%.*]] = sub i32 0, [[UnsignedResult]]
+// CHECK-NEXT: [[Result:%.*]] = select i1 [[IsNeg]], i32 [[NegatedResult]],
i32 [[UnsignedResult]]
+// CHECK-NEXT: store i32 [[Result]], i32* %{{.*}}, align 4
// CHECK: br i1 [[OFlow]]
unsigned result;
@@ -432,7 +434,9 @@
// CHECK-NEXT: [[OVERFLOW_PRE_TRUNC:%.*]] = or i1 {{.*}}, [[UNDERFLOW]]
// CHECK-NEXT: [[TRUNC_OVERFLOW:%.*]] = icmp ugt i64 [[UNSIGNED_RESULT]],
4294967295
// CHECK-NEXT: [[OVERFLOW:%.*]] = or i1 [[OVERFLOW_PRE_TRUNC]],
[[TRUNC_OVERFLOW]]
-// CHECK-NEXT: trunc i64 [[UNSIGNED_RESULT]] to i32
+// CHECK-NEXT: [[NEGATED:%.*]] = sub i64 0, [[UNSIGNED_RESULT]]
+// CHECK-NEXT: [[RESULT:%.*]] = select i1 {{.*}}, i64 [[NEGATED]], i64
[[UNSIGNED_RESULT]]
+// CHECK-NEXT: trunc i64 [[RESULT]] to i32
// CHECK-NEXT: store
unsigned result;
if (__builtin_mul_overflow(y, x, &result))
Index: cfe/trunk/lib/CodeGen/CGBuiltin.cpp
===================================================================
--- cfe/trunk/lib/CodeGen/CGBuiltin.cpp
+++ cfe/trunk/lib/CodeGen/CGBuiltin.cpp
@@ -915,7 +915,11 @@
Overflow = CGF.Builder.CreateOr(Overflow, TruncOverflow);
}
- Result = CGF.Builder.CreateTrunc(UnsignedResult, ResTy);
+ // Negate the product if it would be negative in infinite precision.
+ Result = CGF.Builder.CreateSelect(
+ IsNegative, CGF.Builder.CreateNeg(UnsignedResult), UnsignedResult);
+
+ Result = CGF.Builder.CreateTrunc(Result, ResTy);
}
assert(Overflow && Result && "Missing overflow or result");
Index: cfe/trunk/test/CodeGen/builtins-overflow.c
===================================================================
--- cfe/trunk/test/CodeGen/builtins-overflow.c
+++ cfe/trunk/test/CodeGen/builtins-overflow.c
@@ -373,7 +373,9 @@
// CHECK-NEXT: [[NotNull:%.*]] = icmp ne i32 [[UnsignedResult]], 0
// CHECK-NEXT: [[Underflow:%.*]] = and i1 [[IsNeg]], [[NotNull]]
// CHECK-NEXT: [[OFlow:%.*]] = or i1 [[UnsignedOFlow]], [[Underflow]]
-// CHECK-NEXT: store i32 [[UnsignedResult]], i32* %{{.*}}, align 4
+// CHECK-NEXT: [[NegatedResult:%.*]] = sub i32 0, [[UnsignedResult]]
+// CHECK-NEXT: [[Result:%.*]] = select i1 [[IsNeg]], i32 [[NegatedResult]], i32 [[UnsignedResult]]
+// CHECK-NEXT: store i32 [[Result]], i32* %{{.*}}, align 4
// CHECK: br i1 [[OFlow]]
unsigned result;
@@ -432,7 +434,9 @@
// CHECK-NEXT: [[OVERFLOW_PRE_TRUNC:%.*]] = or i1 {{.*}}, [[UNDERFLOW]]
// CHECK-NEXT: [[TRUNC_OVERFLOW:%.*]] = icmp ugt i64 [[UNSIGNED_RESULT]], 4294967295
// CHECK-NEXT: [[OVERFLOW:%.*]] = or i1 [[OVERFLOW_PRE_TRUNC]], [[TRUNC_OVERFLOW]]
-// CHECK-NEXT: trunc i64 [[UNSIGNED_RESULT]] to i32
+// CHECK-NEXT: [[NEGATED:%.*]] = sub i64 0, [[UNSIGNED_RESULT]]
+// CHECK-NEXT: [[RESULT:%.*]] = select i1 {{.*}}, i64 [[NEGATED]], i64 [[UNSIGNED_RESULT]]
+// CHECK-NEXT: trunc i64 [[RESULT]] to i32
// CHECK-NEXT: store
unsigned result;
if (__builtin_mul_overflow(y, x, &result))
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