guix/gnu/packages/patches/llvm-9-fix-scev-miscompilation.patch

Guix note: this got detected with the test suite of rustc 1.41.1, but
the issue potentially affects all consumers of LLVM.

From 58e8c793d0e43150a6452e971a32d7407a8a7401 Mon Sep 17 00:00:00 2001
From: Tim Northover <tnorthover@apple.com>
Date: Mon, 30 Sep 2019 07:46:52 +0000
Subject: [PATCH] Revert "[SCEV] add no wrap flag for SCEVAddExpr."

This reverts r366419 because the analysis performed is within the context of
the loop and it's only valid to add wrapping flags to "global" expressions if
they're always correct.

llvm-svn: 373184
---
 llvm/lib/Analysis/ScalarEvolution.cpp              | 2 +-
 llvm/test/Analysis/ScalarEvolution/limit-depth.ll  | 2 +-
 llvm/test/Analysis/ScalarEvolution/nsw.ll          | 2 +-
 llvm/test/Analysis/ScalarEvolution/trip-count12.ll | 2 +-
 llvm/test/Analysis/ScalarEvolution/trip-count9.ll  | 8 ++++----
 5 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 354ae05bb841..c29fc5dbccfb 100644
--- llvm/lib/Analysis/ScalarEvolution.cpp
+++ llvm/lib/Analysis/ScalarEvolution.cpp
@@ -4992,7 +4992,7 @@ const SCEV *ScalarEvolution::createSimpleAffineAddRec(PHINode *PN,
   // overflow.
   if (auto *BEInst = dyn_cast<Instruction>(BEValueV))
     if (isLoopInvariant(Accum, L) && isAddRecNeverPoison(BEInst, L))
-      (void)getAddRecExpr(getAddExpr(StartVal, Accum, Flags), Accum, L, Flags);
+      (void)getAddRecExpr(getAddExpr(StartVal, Accum), Accum, L, Flags);
 
   return PHISCEV;
 }
diff --git a/llvm/test/Analysis/ScalarEvolution/limit-depth.ll b/llvm/test/Analysis/ScalarEvolution/limit-depth.ll
index db68a4f84c91..6fdf8c5df974 100644
--- llvm/test/Analysis/ScalarEvolution/limit-depth.ll
+++ llvm/test/Analysis/ScalarEvolution/limit-depth.ll
@@ -46,7 +46,7 @@ define void @test_mul(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e, i32 %f) {
 define void @test_sext(i32 %a, i32 %b, i32 %c, i32 %d, i32 %e, i32 %f) {
 ; CHECK-LABEL: @test_sext
 ; CHECK:        %se2 = sext i64 %iv2.inc to i128
-; CHECK-NEXT:   -->  {(1 + (sext i64 {(sext i32 (1 + %a)<nsw> to i64),+,1}<nsw><%loop> to i128))<nsw>,+,1}<nsw><%loop2>
+; CHECK-NEXT:   -->  {(1 + (sext i64 {(sext i32 (1 + %a) to i64),+,1}<nsw><%loop> to i128))<nsw>,+,1}<nsw><%loop2>
 entry:
   br label %loop
 
diff --git a/llvm/test/Analysis/ScalarEvolution/nsw.ll b/llvm/test/Analysis/ScalarEvolution/nsw.ll
index 69427368625d..ca24f9d4a04b 100644
--- llvm/test/Analysis/ScalarEvolution/nsw.ll
+++ llvm/test/Analysis/ScalarEvolution/nsw.ll
@@ -163,7 +163,7 @@ bb5:                                              ; preds = %bb2
 declare void @f(i32)
 
 ; CHECK-LABEL: nswnowrap
-; CHECK: --> {(1 + %v)<nsw>,+,1}<nsw><%for.body>{{ U: [^ ]+ S: [^ ]+}}{{ *}}Exits: (2 + %v)
+; CHECK: --> {(1 + %v)<nsw>,+,1}<nsw><%for.body>{{ U: [^ ]+ S: [^ ]+}}{{ *}}Exits: (1 + ((1 + %v)<nsw> smax %v))
 define void @nswnowrap(i32 %v, i32* %buf) {
 entry:
   %add = add nsw i32 %v, 1
diff --git a/llvm/test/Analysis/ScalarEvolution/trip-count12.ll b/llvm/test/Analysis/ScalarEvolution/trip-count12.ll
index 5e7d72d5e4f3..d0086ee2e6ac 100644
--- llvm/test/Analysis/ScalarEvolution/trip-count12.ll
+++ llvm/test/Analysis/ScalarEvolution/trip-count12.ll
@@ -1,7 +1,7 @@
 ; RUN: opt < %s -analyze -scalar-evolution | FileCheck %s
 
 ; CHECK: Determining loop execution counts for: @test
-; CHECK: Loop %for.body: backedge-taken count is ((-2 + %len)<nsw> /u 2)
+; CHECK: Loop %for.body: backedge-taken count is ((-2 + %len) /u 2)
 ; CHECK: Loop %for.body: max backedge-taken count is 1073741823
 
 define zeroext i16 @test(i16* nocapture %p, i32 %len) nounwind readonly {
diff --git a/llvm/test/Analysis/ScalarEvolution/trip-count9.ll b/llvm/test/Analysis/ScalarEvolution/trip-count9.ll
index c0a1d12fa00e..9a080b34743f 100644
--- llvm/test/Analysis/ScalarEvolution/trip-count9.ll
+++ llvm/test/Analysis/ScalarEvolution/trip-count9.ll
@@ -179,7 +179,7 @@ exit:
 }
 
 ; CHECK: Determining loop execution counts for: @nsw_startx
-; CHECK: Loop %loop: backedge-taken count is (-1 + (-1 * %x) + ((1 + %x)<nsw> smax %n))
+; CHECK: Loop %loop: backedge-taken count is (-1 + (-1 * %x) + ((1 + %x) smax %n))
 ; CHECK: Loop %loop: max backedge-taken count is -1
 define void @nsw_startx(i4 %n, i4 %x) {
 entry:
@@ -195,7 +195,7 @@ exit:
 }
 
 ; CHECK: Determining loop execution counts for: @nsw_startx_step2
-; CHECK: Loop %loop: backedge-taken count is ((-1 + (-1 * %x) + ((2 + %x)<nsw> smax %n)) /u 2)
+; CHECK: Loop %loop: backedge-taken count is ((-1 + (-1 * %x) + ((2 + %x) smax %n)) /u 2)
 ; CHECK: Loop %loop: max backedge-taken count is 7
 define void @nsw_startx_step2(i4 %n, i4 %x) {
 entry:
@@ -381,7 +381,7 @@ exit:
 }
 
 ; CHECK: Determining loop execution counts for: @even_nsw_startx
-; CHECK: Loop %loop: backedge-taken count is (-1 + (-1 * %x) + ((1 + %x)<nsw> smax (2 * %n)))
+; CHECK: Loop %loop: backedge-taken count is (-1 + (-1 * %x) + ((1 + %x) smax (2 * %n)))
 ; CHECK: Loop %loop: max backedge-taken count is -2
 define void @even_nsw_startx(i4 %n, i4 %x) {
 entry:
@@ -398,7 +398,7 @@ exit:
 }
 
 ; CHECK: Determining loop execution counts for: @even_nsw_startx_step2
-; CHECK: Loop %loop: backedge-taken count is ((-1 + (-1 * %x) + ((2 + %x)<nsw> smax (2 * %n))) /u 2)
+; CHECK: Loop %loop: backedge-taken count is ((-1 + (-1 * %x) + ((2 + %x) smax (2 * %n))) /u 2)
 ; CHECK: Loop %loop: max backedge-taken count is 7
 define void @even_nsw_startx_step2(i4 %n, i4 %x) {
 entry: