[llvm] 6f0ca6f - [JumpThreading] Insert freeze when unfolding select
Nikita Popov via llvm-commits
llvm-commits at lists.llvm.org
Sat May 21 02:24:35 PDT 2022
Author: Nikita Popov
Date: 2022-05-21T11:24:27+02:00
New Revision: 6f0ca6fd2305be860057a1b2c21c6708f4ffdb38
URL: https://github.com/llvm/llvm-project/commit/6f0ca6fd2305be860057a1b2c21c6708f4ffdb38
DIFF: https://github.com/llvm/llvm-project/commit/6f0ca6fd2305be860057a1b2c21c6708f4ffdb38.diff
LOG: [JumpThreading] Insert freeze when unfolding select
JumpThreading may convert selects into branch instructions,
in which case the condition needs to be frozen (as branch on
poison is immediate undefined behavior, unlike select on poison).
The necessary code for this is already in place, this just enables
the option.
Differential Revision: https://reviews.llvm.org/D125869
Added:
Modified:
llvm/include/llvm/Transforms/Scalar/JumpThreading.h
llvm/lib/Transforms/Scalar/JumpThreading.cpp
llvm/test/Transforms/JumpThreading/codesize-loop.ll
llvm/test/Transforms/JumpThreading/select.ll
Removed:
################################################################################
diff --git a/llvm/include/llvm/Transforms/Scalar/JumpThreading.h b/llvm/include/llvm/Transforms/Scalar/JumpThreading.h
index 87f33c1f9ec9f..07db880a6d74b 100644
--- a/llvm/include/llvm/Transforms/Scalar/JumpThreading.h
+++ b/llvm/include/llvm/Transforms/Scalar/JumpThreading.h
@@ -95,7 +95,7 @@ class JumpThreadingPass : public PassInfoMixin<JumpThreadingPass> {
bool InsertFreezeWhenUnfoldingSelect;
public:
- JumpThreadingPass(bool InsertFreezeWhenUnfoldingSelect = false, int T = -1);
+ JumpThreadingPass(bool InsertFreezeWhenUnfoldingSelect = true, int T = -1);
// Glue for old PM.
bool runImpl(Function &F, TargetLibraryInfo *TLI, TargetTransformInfo *TTI,
diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
index 06dd9ff0a75a1..5b1f703ffef0b 100644
--- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp
+++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp
@@ -106,7 +106,7 @@ static cl::opt<bool> PrintLVIAfterJumpThreading(
static cl::opt<bool> JumpThreadingFreezeSelectCond(
"jump-threading-freeze-select-cond",
- cl::desc("Freeze the condition when unfolding select"), cl::init(false),
+ cl::desc("Freeze the condition when unfolding select"), cl::init(true),
cl::Hidden);
static cl::opt<bool> ThreadAcrossLoopHeaders(
@@ -138,7 +138,7 @@ namespace {
public:
static char ID; // Pass identification
- JumpThreading(bool InsertFreezeWhenUnfoldingSelect = false, int T = -1)
+ JumpThreading(bool InsertFreezeWhenUnfoldingSelect = true, int T = -1)
: FunctionPass(ID), Impl(InsertFreezeWhenUnfoldingSelect, T) {
initializeJumpThreadingPass(*PassRegistry::getPassRegistry());
}
diff --git a/llvm/test/Transforms/JumpThreading/codesize-loop.ll b/llvm/test/Transforms/JumpThreading/codesize-loop.ll
index 68d6a99d86deb..3556debfed858 100644
--- a/llvm/test/Transforms/JumpThreading/codesize-loop.ll
+++ b/llvm/test/Transforms/JumpThreading/codesize-loop.ll
@@ -19,7 +19,8 @@ define i32 @test_minsize(i32 %argc, i8** nocapture readonly %argv) local_unnamed
; DEFAULT-NEXT: [[TMP2:%.*]] = mul i32 [[TMP1]], [[TMP1]]
; DEFAULT-NEXT: [[TMP3:%.*]] = mul i32 [[COND]], [[TMP2]]
; DEFAULT-NEXT: [[TMP4:%.*]] = icmp sgt i32 [[COND]], 0
-; DEFAULT-NEXT: br i1 [[TMP4]], label [[TMP5:%.*]], label [[TMP6:%.*]]
+; DEFAULT-NEXT: [[COND_FR:%.*]] = freeze i1 [[TMP4]]
+; DEFAULT-NEXT: br i1 [[COND_FR]], label [[TMP5:%.*]], label [[TMP6:%.*]]
; DEFAULT: 5:
; DEFAULT-NEXT: br label [[TMP6]]
; DEFAULT: 6:
@@ -40,14 +41,15 @@ define i32 @test_minsize(i32 %argc, i8** nocapture readonly %argv) local_unnamed
; OVERIDE-NEXT: [[TMP2:%.*]] = mul i32 [[TMP1]], [[TMP1]]
; OVERIDE-NEXT: [[TMP3:%.*]] = mul i32 [[CALL]], [[TMP2]]
; OVERIDE-NEXT: [[TMP4:%.*]] = icmp sgt i32 [[CALL]], 0
-; OVERIDE-NEXT: br i1 [[TMP4]], label [[COND_END_THREAD]], label [[TMP6:%.*]]
+; OVERIDE-NEXT: [[COND_FR:%.*]] = freeze i1 [[TMP4]]
+; OVERIDE-NEXT: br i1 [[COND_FR]], label [[COND_END_THREAD]], label [[TMP6:%.*]]
; OVERIDE: cond.end.thread:
; OVERIDE-NEXT: [[TMP5:%.*]] = phi i32 [ [[TMP3]], [[COND_END]] ], [ 205962976, [[ENTRY:%.*]] ]
-; OVERIDE-NEXT: [[COND2:%.*]] = phi i32 [ [[CALL]], [[COND_END]] ], [ 46, [[ENTRY]] ]
+; OVERIDE-NEXT: [[COND3:%.*]] = phi i32 [ [[CALL]], [[COND_END]] ], [ 46, [[ENTRY]] ]
; OVERIDE-NEXT: br label [[TMP6]]
; OVERIDE: 6:
; OVERIDE-NEXT: [[TMP7:%.*]] = phi i32 [ [[TMP5]], [[COND_END_THREAD]] ], [ [[TMP3]], [[COND_END]] ]
-; OVERIDE-NEXT: [[TMP8:%.*]] = phi i32 [ [[COND2]], [[COND_END_THREAD]] ], [ 0, [[COND_END]] ]
+; OVERIDE-NEXT: [[TMP8:%.*]] = phi i32 [ [[COND3]], [[COND_END_THREAD]] ], [ 0, [[COND_END]] ]
; OVERIDE-NEXT: [[TMP9:%.*]] = mul i32 [[TMP7]], [[TMP8]]
; OVERIDE-NEXT: [[CALL33:%.*]] = tail call i32 (i8*, ...) @printf(i8* nonnull dereferenceable(1) getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i32 0, i32 0), i32 [[TMP9]])
; OVERIDE-NEXT: ret i32 0
@@ -87,14 +89,15 @@ define i32 @test_optsize(i32 %argc, i8** nocapture readonly %argv) local_unnamed
; DEFAULT-NEXT: [[TMP2:%.*]] = mul i32 [[TMP1]], [[TMP1]]
; DEFAULT-NEXT: [[TMP3:%.*]] = mul i32 [[CALL]], [[TMP2]]
; DEFAULT-NEXT: [[TMP4:%.*]] = icmp sgt i32 [[CALL]], 0
-; DEFAULT-NEXT: br i1 [[TMP4]], label [[COND_END_THREAD]], label [[TMP6:%.*]]
+; DEFAULT-NEXT: [[COND_FR:%.*]] = freeze i1 [[TMP4]]
+; DEFAULT-NEXT: br i1 [[COND_FR]], label [[COND_END_THREAD]], label [[TMP6:%.*]]
; DEFAULT: cond.end.thread:
; DEFAULT-NEXT: [[TMP5:%.*]] = phi i32 [ [[TMP3]], [[COND_END]] ], [ 205962976, [[ENTRY:%.*]] ]
-; DEFAULT-NEXT: [[COND2:%.*]] = phi i32 [ [[CALL]], [[COND_END]] ], [ 46, [[ENTRY]] ]
+; DEFAULT-NEXT: [[COND3:%.*]] = phi i32 [ [[CALL]], [[COND_END]] ], [ 46, [[ENTRY]] ]
; DEFAULT-NEXT: br label [[TMP6]]
; DEFAULT: 6:
; DEFAULT-NEXT: [[TMP7:%.*]] = phi i32 [ [[TMP5]], [[COND_END_THREAD]] ], [ [[TMP3]], [[COND_END]] ]
-; DEFAULT-NEXT: [[TMP8:%.*]] = phi i32 [ [[COND2]], [[COND_END_THREAD]] ], [ 0, [[COND_END]] ]
+; DEFAULT-NEXT: [[TMP8:%.*]] = phi i32 [ [[COND3]], [[COND_END_THREAD]] ], [ 0, [[COND_END]] ]
; DEFAULT-NEXT: [[TMP9:%.*]] = mul i32 [[TMP7]], [[TMP8]]
; DEFAULT-NEXT: [[CALL33:%.*]] = tail call i32 (i8*, ...) @printf(i8* nonnull dereferenceable(1) getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i32 0, i32 0), i32 [[TMP9]])
; DEFAULT-NEXT: ret i32 0
@@ -111,14 +114,15 @@ define i32 @test_optsize(i32 %argc, i8** nocapture readonly %argv) local_unnamed
; OVERIDE-NEXT: [[TMP2:%.*]] = mul i32 [[TMP1]], [[TMP1]]
; OVERIDE-NEXT: [[TMP3:%.*]] = mul i32 [[CALL]], [[TMP2]]
; OVERIDE-NEXT: [[TMP4:%.*]] = icmp sgt i32 [[CALL]], 0
-; OVERIDE-NEXT: br i1 [[TMP4]], label [[COND_END_THREAD]], label [[TMP6:%.*]]
+; OVERIDE-NEXT: [[COND_FR:%.*]] = freeze i1 [[TMP4]]
+; OVERIDE-NEXT: br i1 [[COND_FR]], label [[COND_END_THREAD]], label [[TMP6:%.*]]
; OVERIDE: cond.end.thread:
; OVERIDE-NEXT: [[TMP5:%.*]] = phi i32 [ [[TMP3]], [[COND_END]] ], [ 205962976, [[ENTRY:%.*]] ]
-; OVERIDE-NEXT: [[COND2:%.*]] = phi i32 [ [[CALL]], [[COND_END]] ], [ 46, [[ENTRY]] ]
+; OVERIDE-NEXT: [[COND3:%.*]] = phi i32 [ [[CALL]], [[COND_END]] ], [ 46, [[ENTRY]] ]
; OVERIDE-NEXT: br label [[TMP6]]
; OVERIDE: 6:
; OVERIDE-NEXT: [[TMP7:%.*]] = phi i32 [ [[TMP5]], [[COND_END_THREAD]] ], [ [[TMP3]], [[COND_END]] ]
-; OVERIDE-NEXT: [[TMP8:%.*]] = phi i32 [ [[COND2]], [[COND_END_THREAD]] ], [ 0, [[COND_END]] ]
+; OVERIDE-NEXT: [[TMP8:%.*]] = phi i32 [ [[COND3]], [[COND_END_THREAD]] ], [ 0, [[COND_END]] ]
; OVERIDE-NEXT: [[TMP9:%.*]] = mul i32 [[TMP7]], [[TMP8]]
; OVERIDE-NEXT: [[CALL33:%.*]] = tail call i32 (i8*, ...) @printf(i8* nonnull dereferenceable(1) getelementptr inbounds ([4 x i8], [4 x i8]* @.str, i32 0, i32 0), i32 [[TMP9]])
; OVERIDE-NEXT: ret i32 0
diff --git a/llvm/test/Transforms/JumpThreading/select.ll b/llvm/test/Transforms/JumpThreading/select.ll
index 392cdd386ac1f..4c50be4f01309 100644
--- a/llvm/test/Transforms/JumpThreading/select.ll
+++ b/llvm/test/Transforms/JumpThreading/select.ll
@@ -175,7 +175,8 @@ define void @test_switch_cmp(i1 %cond, i32 %val, i8 %value) nounwind {
; CHECK: L0:
; CHECK-NEXT: [[VAL_PHI:%.*]] = phi i32 [ [[VAL:%.*]], [[ENTRY:%.*]] ]
; CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[VAL_PHI]], 0
-; CHECK-NEXT: br i1 [[CMP]], label [[L1:%.*]], label [[TMP0:%.*]]
+; CHECK-NEXT: [[COND_FR:%.*]] = freeze i1 [[CMP]]
+; CHECK-NEXT: br i1 [[COND_FR]], label [[L1:%.*]], label [[TMP0:%.*]]
; CHECK: 0:
; CHECK-NEXT: [[TMP1:%.*]] = phi i8 [ [[VALUE:%.*]], [[L0]] ]
; CHECK-NEXT: switch i8 [[TMP1]], label [[L3:%.*]] [
@@ -361,22 +362,23 @@ define i32 @unfold3(i32 %u, i32 %v, i32 %w, i32 %x, i32 %y, i32 %z, i32 %j) noun
; CHECK-NEXT: entry:
; CHECK-NEXT: [[ADD3:%.*]] = add nsw i32 [[J:%.*]], 2
; CHECK-NEXT: [[CMP_I:%.*]] = icmp slt i32 [[U:%.*]], [[V:%.*]]
-; CHECK-NEXT: br i1 [[CMP_I]], label [[DOTEXIT_THREAD3:%.*]], label [[COND_FALSE_I:%.*]]
+; CHECK-NEXT: br i1 [[CMP_I]], label [[DOTEXIT_THREAD4:%.*]], label [[COND_FALSE_I:%.*]]
; CHECK: cond.false.i:
; CHECK-NEXT: [[CMP4_I:%.*]] = icmp sgt i32 [[U]], [[V]]
; CHECK-NEXT: br i1 [[CMP4_I]], label [[DOTEXIT_THREAD:%.*]], label [[COND_FALSE_6_I:%.*]]
; CHECK: cond.false.6.i:
; CHECK-NEXT: [[CMP8_I:%.*]] = icmp slt i32 [[W:%.*]], [[X:%.*]]
-; CHECK-NEXT: br i1 [[CMP8_I]], label [[DOTEXIT_THREAD3]], label [[COND_FALSE_10_I:%.*]]
+; CHECK-NEXT: br i1 [[CMP8_I]], label [[DOTEXIT_THREAD4]], label [[COND_FALSE_10_I:%.*]]
; CHECK: cond.false.10.i:
; CHECK-NEXT: [[CMP13_I:%.*]] = icmp sgt i32 [[W]], [[X]]
; CHECK-NEXT: br i1 [[CMP13_I]], label [[DOTEXIT_THREAD]], label [[DOTEXIT:%.*]]
; CHECK: .exit:
; CHECK-NEXT: [[PHITMP:%.*]] = icmp sge i32 [[Y:%.*]], [[Z:%.*]]
-; CHECK-NEXT: br i1 [[PHITMP]], label [[DOTEXIT_THREAD]], label [[DOTEXIT_THREAD3]]
+; CHECK-NEXT: [[COND_FR:%.*]] = freeze i1 [[PHITMP]]
+; CHECK-NEXT: br i1 [[COND_FR]], label [[DOTEXIT_THREAD]], label [[DOTEXIT_THREAD4]]
; CHECK: .exit.thread:
-; CHECK-NEXT: br label [[DOTEXIT_THREAD3]]
-; CHECK: .exit.thread3:
+; CHECK-NEXT: br label [[DOTEXIT_THREAD4]]
+; CHECK: .exit.thread4:
; CHECK-NEXT: [[TMP0:%.*]] = phi i32 [ [[J]], [[DOTEXIT_THREAD]] ], [ [[ADD3]], [[DOTEXIT]] ], [ [[ADD3]], [[ENTRY:%.*]] ], [ [[ADD3]], [[COND_FALSE_6_I]] ]
; CHECK-NEXT: ret i32 [[TMP0]]
;
@@ -416,21 +418,22 @@ define i32 @unfold4(i32 %u, i32 %v, i32 %w, i32 %x, i32 %y, i32 %z, i32 %j) noun
; CHECK-NEXT: br i1 [[CMP_I]], label [[DOTEXIT_THREAD:%.*]], label [[COND_FALSE_I:%.*]]
; CHECK: cond.false.i:
; CHECK-NEXT: [[CMP4_I:%.*]] = icmp sgt i32 [[U]], [[V]]
-; CHECK-NEXT: br i1 [[CMP4_I]], label [[DOTEXIT_THREAD4:%.*]], label [[COND_FALSE_6_I:%.*]]
+; CHECK-NEXT: br i1 [[CMP4_I]], label [[DOTEXIT_THREAD5:%.*]], label [[COND_FALSE_6_I:%.*]]
; CHECK: cond.false.6.i:
; CHECK-NEXT: [[CMP8_I:%.*]] = icmp slt i32 [[W:%.*]], [[X:%.*]]
; CHECK-NEXT: br i1 [[CMP8_I]], label [[DOTEXIT_THREAD]], label [[COND_FALSE_10_I:%.*]]
; CHECK: cond.false.10.i:
; CHECK-NEXT: [[CMP13_I:%.*]] = icmp sgt i32 [[W]], [[X]]
-; CHECK-NEXT: br i1 [[CMP13_I]], label [[DOTEXIT_THREAD4]], label [[DOTEXIT:%.*]]
+; CHECK-NEXT: br i1 [[CMP13_I]], label [[DOTEXIT_THREAD5]], label [[DOTEXIT:%.*]]
; CHECK: .exit:
; CHECK-NEXT: [[CMP19_I:%.*]] = icmp sge i32 [[Y:%.*]], [[Z:%.*]]
; CHECK-NEXT: [[CONV:%.*]] = zext i1 [[CMP19_I]] to i32
; CHECK-NEXT: [[LNOT_I18:%.*]] = icmp eq i32 [[CONV]], 1
-; CHECK-NEXT: br i1 [[LNOT_I18]], label [[DOTEXIT_THREAD]], label [[DOTEXIT_THREAD4]]
+; CHECK-NEXT: [[COND_FR:%.*]] = freeze i1 [[LNOT_I18]]
+; CHECK-NEXT: br i1 [[COND_FR]], label [[DOTEXIT_THREAD]], label [[DOTEXIT_THREAD5]]
; CHECK: .exit.thread:
-; CHECK-NEXT: br label [[DOTEXIT_THREAD4]]
-; CHECK: .exit.thread4:
+; CHECK-NEXT: br label [[DOTEXIT_THREAD5]]
+; CHECK: .exit.thread5:
; CHECK-NEXT: [[TMP0:%.*]] = phi i32 [ [[J]], [[DOTEXIT_THREAD]] ], [ [[ADD3]], [[DOTEXIT]] ], [ [[ADD3]], [[COND_FALSE_I]] ], [ [[ADD3]], [[COND_FALSE_10_I]] ]
; CHECK-NEXT: ret i32 [[TMP0]]
;
@@ -625,16 +628,13 @@ sw.default: ; preds = %if.end, %sw.bb9
br label %for.cond
}
-; FIXME: This is an invalid transform. If %b is false and %x is poison,
-; then the select produces poison (the result of the program is poison).
-; But with this transform, we may be branching on poison, and that is UB.
-
define i32 @TryToUnfoldSelectInCurrBB(i1 %b, i1 %ui, i32 %s, i1 %x) {
; CHECK-LABEL: @TryToUnfoldSelectInCurrBB(
; CHECK-NEXT: entry:
; CHECK-NEXT: br i1 [[B:%.*]], label [[IF_END_THREAD:%.*]], label [[IF_END:%.*]]
; CHECK: if.end:
-; CHECK-NEXT: br i1 [[X:%.*]], label [[TMP0:%.*]], label [[IF_END_THREAD]]
+; CHECK-NEXT: [[COND_FR:%.*]] = freeze i1 [[X:%.*]]
+; CHECK-NEXT: br i1 [[COND_FR]], label [[TMP0:%.*]], label [[IF_END_THREAD]]
; CHECK: 0:
; CHECK-NEXT: br label [[IF_END_THREAD]]
; CHECK: if.end.thread:
More information about the llvm-commits
mailing list