[InstCombine][InstSimplify] Teach decomposeBitTestICmp to look through truncate instr...

This patch teaches decomposeBitTestICmp to look through truncate instructions on the input to the compare. If a truncate is found it will now return the pre-truncated Value and appropriately extend the APInt mask.

This allows some code to be removed from InstSimplify that was doing this functionality.

This allows InstCombine's bit test combining code to match a pre-truncate Value with the same Value appear with an 'and' on another icmp. Or it allows us to combine a truncate to i16 and a truncate to i8. This also required removing the type check from the beginning of getMaskedTypeForICmpPair, but I believe that's ok because we still have to find two values from the input to each icmp that are equal before we'll do any transformation. So the type check was really just serving as an early out.

There was one user of decomposeBitTestICmp that didn't want to look through truncates, so I've added a flag to prevent that behavior when necessary.

Differential Revision: https://reviews.llvm.org/D37158

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312382 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/Analysis/CmpInstAnalysis.h b/include/llvm/Analysis/CmpInstAnalysis.h
index 1079d5a..3cc69d9 100644 (file)
--- a/include/llvm/Analysis/CmpInstAnalysis.h
+++ b/include/llvm/Analysis/CmpInstAnalysis.h
@@ -64,7 +64,8 @@ namespace llvm {
   /// returned predicate is either == or !=. Returns false if decomposition
   /// fails.
   bool decomposeBitTestICmp(Value *LHS, Value *RHS, CmpInst::Predicate &Pred,
-                            Value *&X, APInt &Mask);
+                            Value *&X, APInt &Mask,
+                            bool LookThroughTrunc = true);
 
 } // end namespace llvm
 

diff --git a/lib/Analysis/CmpInstAnalysis.cpp b/lib/Analysis/CmpInstAnalysis.cpp
index c879b87..159c1a2 100644 (file)
--- a/lib/Analysis/CmpInstAnalysis.cpp
+++ b/lib/Analysis/CmpInstAnalysis.cpp
@@ -66,9 +66,11 @@ bool llvm::PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
 
 bool llvm::decomposeBitTestICmp(Value *LHS, Value *RHS,
                                 CmpInst::Predicate &Pred,
-                                Value *&X, APInt &Mask) {
+                                Value *&X, APInt &Mask, bool LookThruTrunc) {
+  using namespace PatternMatch;
+
   const APInt *C;
-  if (!match(RHS, PatternMatch::m_APInt(C)))
+  if (!match(RHS, m_APInt(C)))
     return false;
 
   switch (Pred) {
@@ -132,6 +134,11 @@ bool llvm::decomposeBitTestICmp(Value *LHS, Value *RHS,
     break;
   }
 
-  X = LHS;
+  if (LookThruTrunc && match(LHS, m_Trunc(m_Value(X)))) {
+    Mask = Mask.zext(X->getType()->getScalarSizeInBits());
+  } else {
+    X = LHS;
+  }
+
   return true;
 }

diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp
index d155f6b..94d7181 100644 (file)
--- a/lib/Analysis/InstructionSimplify.cpp
+++ b/lib/Analysis/InstructionSimplify.cpp
@@ -3629,19 +3629,6 @@ static Value *simplifySelectWithFakeICmpEq(Value *CmpLHS, Value *CmpRHS,
   if (!decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, X, Mask))
     return nullptr;
 
-  unsigned BitWidth = TrueVal->getType()->getScalarSizeInBits();
-  if (!BitWidth)
-    return nullptr;
-
-  Value *ExtX;
-  if (match(X, m_Trunc(m_Value(ExtX))) &&
-      (ExtX == TrueVal || ExtX == FalseVal)) {
-    // icmp slt (trunc X), 0  <--> icmp ne (and X, C), 0
-    // icmp sgt (trunc X), -1 <--> icmp eq (and X, C), 0
-    X = ExtX;
-    Mask = Mask.zext(BitWidth);
-  }
-
   return simplifySelectBitTest(TrueVal, FalseVal, X, &Mask,
                                Pred == ICmpInst::ICMP_EQ);
 }

diff --git a/lib/Transforms/InstCombine/InstCombineSelect.cpp b/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 11602ab..83aeda5 100644 (file)
--- a/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -724,7 +724,7 @@ Instruction *InstCombiner::foldSelectInstWithICmp(SelectInst &SI,
       ICmpInst::Predicate Pred = ICI->getPredicate();
       Value *X;
       APInt Mask;
-      if (decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, X, Mask)) {
+      if (decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, X, Mask, false)) {
         if (Mask.isSignMask()) {
           assert(X == CmpLHS && "Expected to use the compare input directly");
           assert(ICmpInst::isEquality(Pred) && "Expected equality predicate");

diff --git a/test/Transforms/InstCombine/bit-checks.ll b/test/Transforms/InstCombine/bit-checks.ll
index 3be6769..1ecd305 100644 (file)
--- a/test/Transforms/InstCombine/bit-checks.ll
+++ b/test/Transforms/InstCombine/bit-checks.ll
@@ -520,12 +520,9 @@ define i32 @main7g(i32 %argc, i32 %argc2, i32 %argc3, i32 %argc4, i32 %argc5) {
 
 define i32 @main8(i32 %argc) {
 ; CHECK-LABEL: @main8(
-; CHECK-NEXT:    [[AND:%.*]] = and i32 [[ARGC:%.*]], 64
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp ne i32 [[AND]], 0
-; CHECK-NEXT:    [[TRUNC2:%.*]] = trunc i32 [[ARGC]] to i8
-; CHECK-NEXT:    [[TOBOOL3:%.*]] = icmp slt i8 [[TRUNC2]], 0
-; CHECK-NEXT:    [[OR_COND:%.*]] = or i1 [[TOBOOL]], [[TOBOOL3]]
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[OR_COND]], i32 2, i32 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[ARGC:%.*]], 192
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 0
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[TMP2]], i32 1, i32 2
 ; CHECK-NEXT:    ret i32 [[RETVAL_0]]
 ;
   %and = and i32 %argc, 64
@@ -539,12 +536,9 @@ define i32 @main8(i32 %argc) {
 
 define i32 @main9(i32 %argc) {
 ; CHECK-LABEL: @main9(
-; CHECK-NEXT:    [[AND:%.*]] = and i32 [[ARGC:%.*]], 64
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp ne i32 [[AND]], 0
-; CHECK-NEXT:    [[TRUNC2:%.*]] = trunc i32 [[ARGC]] to i8
-; CHECK-NEXT:    [[TOBOOL3:%.*]] = icmp slt i8 [[TRUNC2]], 0
-; CHECK-NEXT:    [[OR_COND:%.*]] = and i1 [[TOBOOL]], [[TOBOOL3]]
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[OR_COND]], i32 2, i32 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[ARGC:%.*]], 192
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 192
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[TMP2]], i32 2, i32 1
 ; CHECK-NEXT:    ret i32 [[RETVAL_0]]
 ;
   %and = and i32 %argc, 64
@@ -558,12 +552,9 @@ define i32 @main9(i32 %argc) {
 
 define i32 @main10(i32 %argc) {
 ; CHECK-LABEL: @main10(
-; CHECK-NEXT:    [[AND:%.*]] = and i32 [[ARGC:%.*]], 64
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i32 [[AND]], 0
-; CHECK-NEXT:    [[TRUNC2:%.*]] = trunc i32 [[ARGC]] to i8
-; CHECK-NEXT:    [[TOBOOL3:%.*]] = icmp sgt i8 [[TRUNC2]], -1
-; CHECK-NEXT:    [[OR_COND:%.*]] = and i1 [[TOBOOL]], [[TOBOOL3]]
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[OR_COND]], i32 2, i32 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[ARGC:%.*]], 192
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 0
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[TMP2]], i32 2, i32 1
 ; CHECK-NEXT:    ret i32 [[RETVAL_0]]
 ;
   %and = and i32 %argc, 64
@@ -577,12 +568,9 @@ define i32 @main10(i32 %argc) {
 
 define i32 @main11(i32 %argc) {
 ; CHECK-LABEL: @main11(
-; CHECK-NEXT:    [[AND:%.*]] = and i32 [[ARGC:%.*]], 64
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp eq i32 [[AND]], 0
-; CHECK-NEXT:    [[TRUNC2:%.*]] = trunc i32 [[ARGC]] to i8
-; CHECK-NEXT:    [[TOBOOL3:%.*]] = icmp sgt i8 [[TRUNC2]], -1
-; CHECK-NEXT:    [[OR_COND:%.*]] = or i1 [[TOBOOL]], [[TOBOOL3]]
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[OR_COND]], i32 2, i32 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[ARGC:%.*]], 192
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 192
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[TMP2]], i32 1, i32 2
 ; CHECK-NEXT:    ret i32 [[RETVAL_0]]
 ;
   %and = and i32 %argc, 64
@@ -596,12 +584,9 @@ define i32 @main11(i32 %argc) {
 
 define i32 @main12(i32 %argc) {
 ; CHECK-LABEL: @main12(
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[ARGC:%.*]] to i16
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp slt i16 [[TRUNC]], 0
-; CHECK-NEXT:    [[TRUNC2:%.*]] = trunc i32 [[ARGC]] to i8
-; CHECK-NEXT:    [[TOBOOL3:%.*]] = icmp slt i8 [[TRUNC2]], 0
-; CHECK-NEXT:    [[OR_COND:%.*]] = or i1 [[TOBOOL]], [[TOBOOL3]]
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[OR_COND]], i32 2, i32 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[ARGC:%.*]], 32896
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 0
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[TMP2]], i32 1, i32 2
 ; CHECK-NEXT:    ret i32 [[RETVAL_0]]
 ;
   %trunc = trunc i32 %argc to i16
@@ -615,12 +600,9 @@ define i32 @main12(i32 %argc) {
 
 define i32 @main13(i32 %argc) {
 ; CHECK-LABEL: @main13(
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[ARGC:%.*]] to i16
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp slt i16 [[TRUNC]], 0
-; CHECK-NEXT:    [[TRUNC2:%.*]] = trunc i32 [[ARGC]] to i8
-; CHECK-NEXT:    [[TOBOOL3:%.*]] = icmp slt i8 [[TRUNC2]], 0
-; CHECK-NEXT:    [[OR_COND:%.*]] = and i1 [[TOBOOL]], [[TOBOOL3]]
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[OR_COND]], i32 2, i32 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[ARGC:%.*]], 32896
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 32896
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[TMP2]], i32 2, i32 1
 ; CHECK-NEXT:    ret i32 [[RETVAL_0]]
 ;
   %trunc = trunc i32 %argc to i16
@@ -634,12 +616,9 @@ define i32 @main13(i32 %argc) {
 
 define i32 @main14(i32 %argc) {
 ; CHECK-LABEL: @main14(
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[ARGC:%.*]] to i16
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp sgt i16 [[TRUNC]], -1
-; CHECK-NEXT:    [[TRUNC2:%.*]] = trunc i32 [[ARGC]] to i8
-; CHECK-NEXT:    [[TOBOOL3:%.*]] = icmp sgt i8 [[TRUNC2]], -1
-; CHECK-NEXT:    [[OR_COND:%.*]] = and i1 [[TOBOOL]], [[TOBOOL3]]
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[OR_COND]], i32 2, i32 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[ARGC:%.*]], 32896
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 0
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[TMP2]], i32 2, i32 1
 ; CHECK-NEXT:    ret i32 [[RETVAL_0]]
 ;
   %trunc = trunc i32 %argc to i16
@@ -653,12 +632,9 @@ define i32 @main14(i32 %argc) {
 
 define i32 @main15(i32 %argc) {
 ; CHECK-LABEL: @main15(
-; CHECK-NEXT:    [[TRUNC:%.*]] = trunc i32 [[ARGC:%.*]] to i16
-; CHECK-NEXT:    [[TOBOOL:%.*]] = icmp sgt i16 [[TRUNC]], -1
-; CHECK-NEXT:    [[TRUNC2:%.*]] = trunc i32 [[ARGC]] to i8
-; CHECK-NEXT:    [[TOBOOL3:%.*]] = icmp sgt i8 [[TRUNC2]], -1
-; CHECK-NEXT:    [[OR_COND:%.*]] = or i1 [[TOBOOL]], [[TOBOOL3]]
-; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[OR_COND]], i32 2, i32 1
+; CHECK-NEXT:    [[TMP1:%.*]] = and i32 [[ARGC:%.*]], 32896
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i32 [[TMP1]], 32896
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = select i1 [[TMP2]], i32 1, i32 2
 ; CHECK-NEXT:    ret i32 [[RETVAL_0]]
 ;
   %trunc = trunc i32 %argc to i16