[PredicateInfo] Place predicate info after assume

Place the ssa.copy instructions for assumes after the assume,
instead of before it. Both options are valid, but placing them
afterwards prevents assumes from being replaced with assume(true).
This fixes https://bugs.llvm.org/show_bug.cgi?id=37541 in NewGVN
and will avoid a similar issue in SCCP when we handle more
predicate infos.

Differential Revision: https://reviews.llvm.org/D83631

diff --git a/llvm/lib/Transforms/Utils/PredicateInfo.cpp b/llvm/lib/Transforms/Utils/PredicateInfo.cpp
index c81efd7..6ac2d64 100644 (file)
--- a/llvm/lib/Transforms/Utils/PredicateInfo.cpp
+++ b/llvm/lib/Transforms/Utils/PredicateInfo.cpp
@@ -205,14 +205,14 @@ struct ValueDFS_Compare {
     // numbering will say the placed predicaeinfos should go first (IE
     // LN_beginning), so we won't be in this function. For assumes, we will end
     // up here, beause we need to order the def we will place relative to the
-    // assume.  So for the purpose of ordering, we pretend the def is the assume
-    // because that is where we will insert the info.
+    // assume.  So for the purpose of ordering, we pretend the def is right
+    // after the assume, because that is where we will insert the info.
     if (!VD.U) {
       assert(VD.PInfo &&
              "No def, no use, and no predicateinfo should not occur");
       assert(isa<PredicateAssume>(VD.PInfo) &&
              "Middle of block should only occur for assumes");
-      return cast<PredicateAssume>(VD.PInfo)->AssumeInst;
+      return cast<PredicateAssume>(VD.PInfo)->AssumeInst->getNextNode();
     }
     return nullptr;
   }
@@ -621,7 +621,9 @@ Value *PredicateInfoBuilder::materializeStack(unsigned int &Counter,
       auto *PAssume = dyn_cast<PredicateAssume>(ValInfo);
       assert(PAssume &&
              "Should not have gotten here without it being an assume");
-      IRBuilder<> B(PAssume->AssumeInst);
+      // Insert the predicate directly after the assume. While it also holds
+      // directly before it, assume(i1 true) is not a useful fact.
+      IRBuilder<> B(PAssume->AssumeInst->getNextNode());
       Function *IF = getCopyDeclaration(F.getParent(), Op->getType());
       if (IF->users().empty())
         PI.CreatedDeclarations.insert(IF);

diff --git a/llvm/test/Transforms/NewGVN/assume-equal.ll b/llvm/test/Transforms/NewGVN/assume-equal.ll
index a200756..d67105f 100644 (file)
--- a/llvm/test/Transforms/NewGVN/assume-equal.ll
+++ b/llvm/test/Transforms/NewGVN/assume-equal.ll
@@ -7,7 +7,7 @@ define float @_Z1if(float %p) {
 ; CHECK-NEXT:    [[P_ADDR:%.*]] = alloca float, align 4
 ; CHECK-NEXT:    store float [[P:%.*]], float* [[P_ADDR]], align 4
 ; CHECK-NEXT:    [[CMP:%.*]] = fcmp ueq float [[P]], 3.000000e+00
-; CHECK-NEXT:    call void @llvm.assume(i1 true)
+; CHECK-NEXT:    call void @llvm.assume(i1 [[CMP]])
 ; CHECK-NEXT:    ret float [[P]]
 ;
 entry:
@@ -26,7 +26,7 @@ define i32 @_Z1ii(i32 %p) {
 ; CHECK-LABEL: @_Z1ii(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[P:%.*]], 42
-; CHECK-NEXT:    call void @llvm.assume(i1 true)
+; CHECK-NEXT:    call void @llvm.assume(i1 [[CMP]])
 ; CHECK-NEXT:    br i1 true, label [[BB2:%.*]], label [[BB2]]
 ; CHECK:       bb2:
 ; CHECK-NEXT:    br i1 true, label [[BB2]], label [[BB2]]
@@ -50,7 +50,7 @@ define i32 @_Z1ij(i32 %p) {
 ; CHECK-LABEL: @_Z1ij(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[P:%.*]], 42
-; CHECK-NEXT:    call void @llvm.assume(i1 true)
+; CHECK-NEXT:    call void @llvm.assume(i1 [[CMP]])
 ; CHECK-NEXT:    br i1 true, label [[BB2:%.*]], label [[BB2]]
 ; CHECK:       bb2:
 ; CHECK-NEXT:    call void @llvm.assume(i1 true)
@@ -76,10 +76,10 @@ define i32 @_Z1ik(i32 %p) {
 ; CHECK-LABEL: @_Z1ik(
 ; CHECK-NEXT:  entry:
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[P:%.*]], 42
-; CHECK-NEXT:    call void @llvm.assume(i1 true)
+; CHECK-NEXT:    call void @llvm.assume(i1 [[CMP]])
 ; CHECK-NEXT:    br i1 true, label [[BB2:%.*]], label [[BB3:%.*]]
 ; CHECK:       bb2:
-; CHECK-NEXT:    call void @llvm.assume(i1 true)
+; CHECK-NEXT:    call void @llvm.assume(i1 false)
 ; CHECK-NEXT:    ret i32 15
 ; CHECK:       bb3:
 ; CHECK-NEXT:    store i8 undef, i8* null, align 1

diff --git a/llvm/test/Transforms/NewGVN/assumes.ll b/llvm/test/Transforms/NewGVN/assumes.ll
index ea20b38..eee302a 100644 (file)
--- a/llvm/test/Transforms/NewGVN/assumes.ll
+++ b/llvm/test/Transforms/NewGVN/assumes.ll
@@ -4,7 +4,7 @@
 define i32 @test1(i32 %arg) {
 ; CHECK-LABEL: @test1(
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp sge i32 [[ARG:%.*]], 5
-; CHECK-NEXT:    call void @llvm.assume(i1 true)
+; CHECK-NEXT:    call void @llvm.assume(i1 [[CMP]])
 ; CHECK-NEXT:    ret i32 [[ARG]]
 ;
   %cmp = icmp sge i32 %arg, 5
@@ -18,7 +18,7 @@ define i32 @test2(i32 %arg, i1 %b) {
 ; CHECK:       bb:
 ; CHECK-NEXT:    [[A:%.*]] = phi i32 [ 1, [[TMP0:%.*]] ], [ 2, [[BB]] ]
 ; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[ARG:%.*]], [[A]]
-; CHECK-NEXT:    call void @llvm.assume(i1 true)
+; CHECK-NEXT:    call void @llvm.assume(i1 [[CMP]])
 ; CHECK-NEXT:    br i1 [[B:%.*]], label [[BB]], label [[END:%.*]]
 ; CHECK:       end:
 ; CHECK-NEXT:    ret i32 [[ARG]]

diff --git a/llvm/test/Transforms/Util/PredicateInfo/testandor.ll b/llvm/test/Transforms/Util/PredicateInfo/testandor.ll
index c84562c..cd1491e 100644 (file)
--- a/llvm/test/Transforms/Util/PredicateInfo/testandor.ll
+++ b/llvm/test/Transforms/Util/PredicateInfo/testandor.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -print-predicateinfo < %s 2>&1 | FileCheck %s
+; RUN: opt -print-predicateinfo -disable-output < %s 2>&1 | FileCheck %s
 
 declare void @foo(i1)
 declare void @bar(i32)
@@ -136,18 +136,18 @@ define void @testandassume(i32 %x, i32 %y) {
 ; CHECK-NEXT:    [[XZ:%.*]] = icmp eq i32 [[X:%.*]], 0
 ; CHECK-NEXT:    [[YZ:%.*]] = icmp eq i32 [[Y:%.*]], 0
 ; CHECK-NEXT:    [[Z:%.*]] = and i1 [[XZ]], [[YZ]]
-; CHECK:         [[TMP1:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[XZ]])
-; CHECK:         [[TMP2:%.*]] = call i32 @llvm.ssa.copy.{{.+}}(i32 [[X]])
+; CHECK-NEXT:    call void @llvm.assume(i1 [[Z]])
+; CHECK:         [[TMP1:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[Z]])
+; CHECK:         [[TMP2:%.*]] = call i32 @llvm.ssa.copy.{{.+}}(i32 [[Y]])
 ; CHECK:         [[TMP3:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[YZ]])
-; CHECK:         [[TMP4:%.*]] = call i32 @llvm.ssa.copy.{{.+}}(i32 [[Y]])
-; CHECK:         [[TMP5:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[Z]])
-; CHECK-NEXT:    call void @llvm.assume(i1 [[TMP5]])
-; CHECK:         [[DOT0:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[TMP1]])
-; CHECK:         [[DOT01:%.*]] = call i32 @llvm.ssa.copy.{{.+}}(i32 [[TMP2]])
+; CHECK:         [[TMP4:%.*]] = call i32 @llvm.ssa.copy.{{.+}}(i32 [[X]])
+; CHECK:         [[TMP5:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[XZ]])
+; CHECK:         [[DOT0:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[TMP5]])
+; CHECK:         [[DOT01:%.*]] = call i32 @llvm.ssa.copy.{{.+}}(i32 [[TMP4]])
 ; CHECK:         [[DOT02:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[TMP3]])
-; CHECK:         [[DOT03:%.*]] = call i32 @llvm.ssa.copy.{{.+}}(i32 [[TMP4]])
-; CHECK:         [[DOT04:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[TMP5]])
-; CHECK-NEXT:    br i1 [[TMP5]], label [[BOTH:%.*]], label [[NOPE:%.*]]
+; CHECK:         [[DOT03:%.*]] = call i32 @llvm.ssa.copy.{{.+}}(i32 [[TMP2]])
+; CHECK:         [[DOT04:%.*]] = call i1 @llvm.ssa.copy.{{.+}}(i1 [[TMP1]])
+; CHECK-NEXT:    br i1 [[TMP1]], label [[BOTH:%.*]], label [[NOPE:%.*]]
 ; CHECK:       both:
 ; CHECK-NEXT:    call void @foo(i1 [[DOT0]])
 ; CHECK-NEXT:    call void @foo(i1 [[DOT02]])