Sanjay Patel 85b289377b [SCCP] convert signed div/rem to unsigned for non-negative operands, 2nd try
The original commit ( fe1f3cfc2669 ) was reverted because it could
crash / assert when trying to fold a value that was replaced
by a constant. In that case, there might not be an entry for the
constant in the solver yet.

This version adds a check for that possibility along with tests to
exercise that pattern (they used to crash).

Original commit message:
This extends the transform added with D81756 to handle div/rem opcodes.
For example:
https://alive2.llvm.org/ce/z/cX6za6

This replicates part of what CVP already does, but the motivating example
from issue #57472 demonstrates a phase ordering problem - we convert
branches to select before CVP runs and miss the transform.

Differential Revision: https://reviews.llvm.org/D133198
2022-09-07 11:56:29 -04:00

25 lines
611 B
LLVM

; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt -passes=ipsccp -S < %s | FileCheck %s
@g = internal global i32 42, align 4
define i32 @sdiv_const_undef() {
; CHECK-LABEL: @sdiv_const_undef(
; CHECK-NEXT: [[D:%.*]] = sdiv i32 42, poison
; CHECK-NEXT: ret i32 [[D]]
;
%i = load i32, ptr @g, align 4
%d = sdiv i32 %i, poison
ret i32 %d
}
define i32 @sdiv_undef_const() {
; CHECK-LABEL: @sdiv_undef_const(
; CHECK-NEXT: [[D:%.*]] = sdiv i32 poison, 42
; CHECK-NEXT: ret i32 [[D]]
;
%i = load i32, ptr @g, align 4
%d = sdiv i32 poison, %i
ret i32 %d
}