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clang-p2996/llvm/test/Transforms/InstCombine/select-divrem.ll
Sanjay Patel 452279efe2 [InstCombine] prevent miscompiles from select-of-div/rem transform 
This avoids the danger shown in issue #60906.
There were no regression tests for these patterns, so these potential
failures have been around for a long time.

We freeze the condition and preserve the optimization because
getting rid of a div/rem is always a win.

Here are a couple of examples that can be corrected by freezing the
condition:
https://alive2.llvm.org/ce/z/sXHTTC

Differential Revision: https://reviews.llvm.org/D144671
2023-03-01 08:54:23 -05:00

216 lines
7.1 KiB
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; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
; RUN: opt < %s -passes=instcombine -S | FileCheck %s
; It is a miscompile in most of these tests if we
; execute div/rem without freezing the potentially
; poison condition value.
define i5 @sdiv_common_divisor(i1 %b, i5 %x, i5 %y, i5 %z) {
; CHECK-LABEL: @sdiv_common_divisor(
; CHECK-NEXT: [[TMP1:%.*]] = freeze i1 [[B:%.*]]
; CHECK-NEXT: [[SEL_V:%.*]] = select i1 [[TMP1]], i5 [[Z:%.*]], i5 [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = sdiv i5 [[SEL_V]], [[X:%.*]]
; CHECK-NEXT: ret i5 [[SEL]]
;
%r1 = sdiv i5 %y, %x
%r2 = sdiv i5 %z, %x
%sel = select i1 %b, i5 %r2, i5 %r1
ret i5 %sel
}
define i5 @srem_common_divisor(i1 %b, i5 %x, i5 %y, i5 %z) {
; CHECK-LABEL: @srem_common_divisor(
; CHECK-NEXT: [[TMP1:%.*]] = freeze i1 [[B:%.*]]
; CHECK-NEXT: [[SEL_V:%.*]] = select i1 [[TMP1]], i5 [[Z:%.*]], i5 [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = srem i5 [[SEL_V]], [[X:%.*]]
; CHECK-NEXT: ret i5 [[SEL]]
;
%r1 = srem i5 %y, %x
%r2 = srem i5 %z, %x
%sel = select i1 %b, i5 %r2, i5 %r1
ret i5 %sel
}
; This is ok without freeze because UB can only happen with x==0,
; and that occurs in the original code.
define i5 @udiv_common_divisor(i1 %b, i5 %x, i5 %y, i5 %z) {
; CHECK-LABEL: @udiv_common_divisor(
; CHECK-NEXT: [[SEL_V:%.*]] = select i1 [[B:%.*]], i5 [[Z:%.*]], i5 [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = udiv i5 [[SEL_V]], [[X:%.*]]
; CHECK-NEXT: ret i5 [[SEL]]
;
%r1 = udiv i5 %y, %x
%r2 = udiv i5 %z, %x
%sel = select i1 %b, i5 %r2, i5 %r1
ret i5 %sel
}
; This is ok without freeze because UB can only happen with x==0,
; and that occurs in the original code.
define i5 @urem_common_divisor(i1 %b, i5 %x, i5 %y, i5 %z) {
; CHECK-LABEL: @urem_common_divisor(
; CHECK-NEXT: [[SEL_V:%.*]] = select i1 [[B:%.*]], i5 [[Z:%.*]], i5 [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = urem i5 [[SEL_V]], [[X:%.*]]
; CHECK-NEXT: ret i5 [[SEL]]
;
%r1 = urem i5 %y, %x
%r2 = urem i5 %z, %x
%sel = select i1 %b, i5 %r2, i5 %r1
ret i5 %sel
}
define i5 @sdiv_common_dividend(i1 %b, i5 %x, i5 %y, i5 %z) {
; CHECK-LABEL: @sdiv_common_dividend(
; CHECK-NEXT: [[TMP1:%.*]] = freeze i1 [[B:%.*]]
; CHECK-NEXT: [[SEL_V:%.*]] = select i1 [[TMP1]], i5 [[Z:%.*]], i5 [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = sdiv i5 [[X:%.*]], [[SEL_V]]
; CHECK-NEXT: ret i5 [[SEL]]
;
%r1 = sdiv i5 %x, %y
%r2 = sdiv i5 %x, %z
%sel = select i1 %b, i5 %r2, i5 %r1
ret i5 %sel
}
define i5 @srem_common_dividend(i1 %b, i5 %x, i5 %y, i5 %z) {
; CHECK-LABEL: @srem_common_dividend(
; CHECK-NEXT: [[TMP1:%.*]] = freeze i1 [[B:%.*]]
; CHECK-NEXT: [[SEL_V:%.*]] = select i1 [[TMP1]], i5 [[Z:%.*]], i5 [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = srem i5 [[X:%.*]], [[SEL_V]]
; CHECK-NEXT: ret i5 [[SEL]]
;
%r1 = srem i5 %x, %y
%r2 = srem i5 %x, %z
%sel = select i1 %b, i5 %r2, i5 %r1
ret i5 %sel
}
define i5 @udiv_common_dividend(i1 %b, i5 %x, i5 %y, i5 %z) {
; CHECK-LABEL: @udiv_common_dividend(
; CHECK-NEXT: [[TMP1:%.*]] = freeze i1 [[B:%.*]]
; CHECK-NEXT: [[SEL_V:%.*]] = select i1 [[TMP1]], i5 [[Z:%.*]], i5 [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = udiv i5 [[X:%.*]], [[SEL_V]]
; CHECK-NEXT: ret i5 [[SEL]]
;
%r1 = udiv i5 %x, %y
%r2 = udiv i5 %x, %z
%sel = select i1 %b, i5 %r2, i5 %r1
ret i5 %sel
}
define i5 @urem_common_dividend(i1 %b, i5 %x, i5 %y, i5 %z) {
; CHECK-LABEL: @urem_common_dividend(
; CHECK-NEXT: [[TMP1:%.*]] = freeze i1 [[B:%.*]]
; CHECK-NEXT: [[SEL_V:%.*]] = select i1 [[TMP1]], i5 [[Z:%.*]], i5 [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = urem i5 [[X:%.*]], [[SEL_V]]
; CHECK-NEXT: ret i5 [[SEL]]
;
%r1 = urem i5 %x, %y
%r2 = urem i5 %x, %z
%sel = select i1 %b, i5 %r2, i5 %r1
ret i5 %sel
}
; Repeat the above tests, but guarantee that the select
; condition is not poison via argument attribute. That
; makes it safe to execute the select before div/rem
; without needing to freeze the condition.
define i5 @sdiv_common_divisor_defined_cond(i1 noundef %b, i5 %x, i5 %y, i5 %z) {
; CHECK-LABEL: @sdiv_common_divisor_defined_cond(
; CHECK-NEXT: [[SEL_V:%.*]] = select i1 [[B:%.*]], i5 [[Z:%.*]], i5 [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = sdiv i5 [[SEL_V]], [[X:%.*]]
; CHECK-NEXT: ret i5 [[SEL]]
;
%r1 = sdiv i5 %y, %x
%r2 = sdiv i5 %z, %x
%sel = select i1 %b, i5 %r2, i5 %r1
ret i5 %sel
}
define i5 @srem_common_divisor_defined_cond(i1 noundef %b, i5 %x, i5 %y, i5 %z) {
; CHECK-LABEL: @srem_common_divisor_defined_cond(
; CHECK-NEXT: [[SEL_V:%.*]] = select i1 [[B:%.*]], i5 [[Z:%.*]], i5 [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = srem i5 [[SEL_V]], [[X:%.*]]
; CHECK-NEXT: ret i5 [[SEL]]
;
%r1 = srem i5 %y, %x
%r2 = srem i5 %z, %x
%sel = select i1 %b, i5 %r2, i5 %r1
ret i5 %sel
}
define i5 @udiv_common_divisor_defined_cond(i1 noundef %b, i5 %x, i5 %y, i5 %z) {
; CHECK-LABEL: @udiv_common_divisor_defined_cond(
; CHECK-NEXT: [[SEL_V:%.*]] = select i1 [[B:%.*]], i5 [[Z:%.*]], i5 [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = udiv i5 [[SEL_V]], [[X:%.*]]
; CHECK-NEXT: ret i5 [[SEL]]
;
%r1 = udiv i5 %y, %x
%r2 = udiv i5 %z, %x
%sel = select i1 %b, i5 %r2, i5 %r1
ret i5 %sel
}
define i5 @urem_common_divisor_defined_cond(i1 noundef %b, i5 %x, i5 %y, i5 %z) {
; CHECK-LABEL: @urem_common_divisor_defined_cond(
; CHECK-NEXT: [[SEL_V:%.*]] = select i1 [[B:%.*]], i5 [[Z:%.*]], i5 [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = urem i5 [[SEL_V]], [[X:%.*]]
; CHECK-NEXT: ret i5 [[SEL]]
;
%r1 = urem i5 %y, %x
%r2 = urem i5 %z, %x
%sel = select i1 %b, i5 %r2, i5 %r1
ret i5 %sel
}
define i5 @sdiv_common_dividend_defined_cond(i1 noundef %b, i5 %x, i5 %y, i5 %z) {
; CHECK-LABEL: @sdiv_common_dividend_defined_cond(
; CHECK-NEXT: [[SEL_V:%.*]] = select i1 [[B:%.*]], i5 [[Z:%.*]], i5 [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = sdiv i5 [[X:%.*]], [[SEL_V]]
; CHECK-NEXT: ret i5 [[SEL]]
;
%r1 = sdiv i5 %x, %y
%r2 = sdiv i5 %x, %z
%sel = select i1 %b, i5 %r2, i5 %r1
ret i5 %sel
}
define i5 @srem_common_dividend_defined_cond(i1 noundef %b, i5 %x, i5 %y, i5 %z) {
; CHECK-LABEL: @srem_common_dividend_defined_cond(
; CHECK-NEXT: [[SEL_V:%.*]] = select i1 [[B:%.*]], i5 [[Z:%.*]], i5 [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = srem i5 [[X:%.*]], [[SEL_V]]
; CHECK-NEXT: ret i5 [[SEL]]
;
%r1 = srem i5 %x, %y
%r2 = srem i5 %x, %z
%sel = select i1 %b, i5 %r2, i5 %r1
ret i5 %sel
}
define i5 @udiv_common_dividend_defined_cond(i1 noundef %b, i5 %x, i5 %y, i5 %z) {
; CHECK-LABEL: @udiv_common_dividend_defined_cond(
; CHECK-NEXT: [[SEL_V:%.*]] = select i1 [[B:%.*]], i5 [[Z:%.*]], i5 [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = udiv i5 [[X:%.*]], [[SEL_V]]
; CHECK-NEXT: ret i5 [[SEL]]
;
%r1 = udiv i5 %x, %y
%r2 = udiv i5 %x, %z
%sel = select i1 %b, i5 %r2, i5 %r1
ret i5 %sel
}
define i5 @urem_common_dividend_defined_cond(i1 noundef %b, i5 %x, i5 %y, i5 %z) {
; CHECK-LABEL: @urem_common_dividend_defined_cond(
; CHECK-NEXT: [[SEL_V:%.*]] = select i1 [[B:%.*]], i5 [[Z:%.*]], i5 [[Y:%.*]]
; CHECK-NEXT: [[SEL:%.*]] = urem i5 [[X:%.*]], [[SEL_V]]
; CHECK-NEXT: ret i5 [[SEL]]
;
%r1 = urem i5 %x, %y
%r2 = urem i5 %x, %z
%sel = select i1 %b, i5 %r2, i5 %r1
ret i5 %sel
}
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