[llvm-branch-commits] [llvm] cb2e598 - [LoopIdiom] 'left-shift until bittest' idiom: support constant bit mask
Roman Lebedev via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Wed Dec 23 11:33:10 PST 2020
Author: Roman Lebedev
Date: 2020-12-23T22:28:09+03:00
New Revision: cb2e5980bae3bead524895f4f36e4f71cd764a1b
URL: https://github.com/llvm/llvm-project/commit/cb2e5980bae3bead524895f4f36e4f71cd764a1b
DIFF: https://github.com/llvm/llvm-project/commit/cb2e5980bae3bead524895f4f36e4f71cd764a1b.diff
LOG: [LoopIdiom] 'left-shift until bittest' idiom: support constant bit mask
The handing of the case where the mask is a constant is trivial,
if said constant is a power of two, the bit in question is log2(mask),
rest just works.
Reviewed By: craig.topper
Differential Revision: https://reviews.llvm.org/D91725
Added:
Modified:
llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
llvm/test/Transforms/LoopIdiom/X86/left-shift-until-bittest.ll
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
index e87ebaf4ad94..f71f320aceb5 100644
--- a/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopIdiomRecognize.cpp
@@ -2000,9 +2000,14 @@ static bool detectShiftUntilBitTestIdiom(Loop *CurLoop, Value *&BaseX,
m_LoopInvariant(m_Shl(m_One(), m_Value(BitPos)),
CurLoop))));
};
+ auto MatchConstantBitMask = [&]() {
+ return ICmpInst::isEquality(Pred) && match(CmpRHS, m_Zero()) &&
+ match(CmpLHS, m_And(m_Value(CurrX),
+ m_CombineAnd(m_Value(BitMask), m_Power2()))) &&
+ (BitPos = ConstantExpr::getExactLogBase2(cast<Constant>(BitMask)));
+ };
- if (!MatchVariableBitMask()) {
- // FIXME: support constant bit mask.
+ if (!MatchVariableBitMask() && !MatchConstantBitMask()) {
// FIXME: support sign bit test (use llvm::decomposeBitTestICmp()).
LLVM_DEBUG(dbgs() << DEBUG_TYPE " Bad backedge comparison.\n");
return false;
diff --git a/llvm/test/Transforms/LoopIdiom/X86/left-shift-until-bittest.ll b/llvm/test/Transforms/LoopIdiom/X86/left-shift-until-bittest.ll
index 3b128aa7b1d2..b5061efe73a5 100644
--- a/llvm/test/Transforms/LoopIdiom/X86/left-shift-until-bittest.ll
+++ b/llvm/test/Transforms/LoopIdiom/X86/left-shift-until-bittest.ll
@@ -144,22 +144,47 @@ end:
}
define i32 @p2_constant_mask_24thbit(i32 %x) {
-; ALL-LABEL: @p2_constant_mask_24thbit(
-; ALL-NEXT: entry:
-; ALL-NEXT: br label [[LOOP:%.*]], [[DBG46:!dbg !.*]]
-; ALL: loop:
-; ALL-NEXT: [[X_CURR:%.*]] = phi i32 [ [[X:%.*]], [[ENTRY:%.*]] ], [ [[X_NEXT:%.*]], [[LOOP]] ], [[DBG47:!dbg !.*]]
-; ALL-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR]], [[META42:metadata !.*]], metadata !DIExpression()), [[DBG47]]
-; ALL-NEXT: [[X_CURR_BITMASKED:%.*]] = and i32 [[X_CURR]], 16777216, [[DBG48:!dbg !.*]]
-; ALL-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR_BITMASKED]], [[META43:metadata !.*]], metadata !DIExpression()), [[DBG48]]
-; ALL-NEXT: [[X_CURR_ISBITUNSET:%.*]] = icmp eq i32 [[X_CURR_BITMASKED]], 0, [[DBG49:!dbg !.*]]
-; ALL-NEXT: call void @llvm.dbg.value(metadata i1 [[X_CURR_ISBITUNSET]], [[META44:metadata !.*]], metadata !DIExpression()), [[DBG49]]
-; ALL-NEXT: [[X_NEXT]] = shl i32 [[X_CURR]], 1, [[DBG50:!dbg !.*]]
-; ALL-NEXT: call void @llvm.dbg.value(metadata i32 [[X_NEXT]], [[META45:metadata !.*]], metadata !DIExpression()), [[DBG50]]
-; ALL-NEXT: br i1 [[X_CURR_ISBITUNSET]], label [[LOOP]], label [[END:%.*]], [[DBG51:!dbg !.*]]
-; ALL: end:
-; ALL-NEXT: [[X_CURR_LCSSA:%.*]] = phi i32 [ [[X_CURR]], [[LOOP]] ], [[DBG47]]
-; ALL-NEXT: ret i32 [[X_CURR_LCSSA]], [[DBG52:!dbg !.*]]
+; LZCNT-LABEL: @p2_constant_mask_24thbit(
+; LZCNT-NEXT: entry:
+; LZCNT-NEXT: [[X_MASKED:%.*]] = and i32 [[X:%.*]], 33554431, [[DBG46:!dbg !.*]]
+; LZCNT-NEXT: [[X_MASKED_NUMLEADINGZEROS:%.*]] = call i32 @llvm.ctlz.i32(i32 [[X_MASKED]], i1 true), [[DBG46]]
+; LZCNT-NEXT: [[X_MASKED_NUMACTIVEBITS:%.*]] = sub i32 32, [[X_MASKED_NUMLEADINGZEROS]], [[DBG46]]
+; LZCNT-NEXT: [[X_MASKED_LEADINGONEPOS:%.*]] = add i32 [[X_MASKED_NUMACTIVEBITS]], -1, [[DBG46]]
+; LZCNT-NEXT: [[LOOP_BACKEDGETAKENCOUNT:%.*]] = sub i32 24, [[X_MASKED_LEADINGONEPOS]], [[DBG46]]
+; LZCNT-NEXT: [[LOOP_TRIPCOUNT:%.*]] = add nuw i32 [[LOOP_BACKEDGETAKENCOUNT]], 1, [[DBG46]]
+; LZCNT-NEXT: [[X_CURR:%.*]] = shl i32 [[X]], [[LOOP_BACKEDGETAKENCOUNT]], [[DBG46]]
+; LZCNT-NEXT: [[X_NEXT:%.*]] = shl i32 [[X]], [[LOOP_TRIPCOUNT]], [[DBG46]]
+; LZCNT-NEXT: br label [[LOOP:%.*]], [[DBG47:!dbg !.*]]
+; LZCNT: loop:
+; LZCNT-NEXT: [[TMP0:%.*]] = phi i32 [ [[X]], [[ENTRY:%.*]] ], [ [[X_NEXT]], [[LOOP]] ], [[DBG46]]
+; LZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR]], [[META42:metadata !.*]], metadata !DIExpression()), [[DBG46]]
+; LZCNT-NEXT: [[X_CURR_BITMASKED:%.*]] = and i32 [[X_CURR]], 16777216, [[DBG48:!dbg !.*]]
+; LZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR_BITMASKED]], [[META43:metadata !.*]], metadata !DIExpression()), [[DBG48]]
+; LZCNT-NEXT: [[X_CURR_ISBITUNSET:%.*]] = icmp eq i32 [[X_CURR_BITMASKED]], 0, [[DBG49:!dbg !.*]]
+; LZCNT-NEXT: call void @llvm.dbg.value(metadata i1 [[X_CURR_ISBITUNSET]], [[META44:metadata !.*]], metadata !DIExpression()), [[DBG49]]
+; LZCNT-NEXT: [[TMP1:%.*]] = shl i32 [[X_CURR]], 1, [[DBG50:!dbg !.*]]
+; LZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_NEXT]], [[META45:metadata !.*]], metadata !DIExpression()), [[DBG50]]
+; LZCNT-NEXT: br i1 true, label [[END:%.*]], label [[LOOP]], [[DBG51:!dbg !.*]]
+; LZCNT: end:
+; LZCNT-NEXT: [[X_CURR_LCSSA:%.*]] = phi i32 [ [[X_CURR]], [[LOOP]] ], [[DBG46]]
+; LZCNT-NEXT: ret i32 [[X_CURR_LCSSA]], [[DBG52:!dbg !.*]]
+;
+; NOLZCNT-LABEL: @p2_constant_mask_24thbit(
+; NOLZCNT-NEXT: entry:
+; NOLZCNT-NEXT: br label [[LOOP:%.*]], [[DBG46:!dbg !.*]]
+; NOLZCNT: loop:
+; NOLZCNT-NEXT: [[X_CURR:%.*]] = phi i32 [ [[X:%.*]], [[ENTRY:%.*]] ], [ [[X_NEXT:%.*]], [[LOOP]] ], [[DBG47:!dbg !.*]]
+; NOLZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR]], [[META42:metadata !.*]], metadata !DIExpression()), [[DBG47]]
+; NOLZCNT-NEXT: [[X_CURR_BITMASKED:%.*]] = and i32 [[X_CURR]], 16777216, [[DBG48:!dbg !.*]]
+; NOLZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR_BITMASKED]], [[META43:metadata !.*]], metadata !DIExpression()), [[DBG48]]
+; NOLZCNT-NEXT: [[X_CURR_ISBITUNSET:%.*]] = icmp eq i32 [[X_CURR_BITMASKED]], 0, [[DBG49:!dbg !.*]]
+; NOLZCNT-NEXT: call void @llvm.dbg.value(metadata i1 [[X_CURR_ISBITUNSET]], [[META44:metadata !.*]], metadata !DIExpression()), [[DBG49]]
+; NOLZCNT-NEXT: [[X_NEXT]] = shl i32 [[X_CURR]], 1, [[DBG50:!dbg !.*]]
+; NOLZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_NEXT]], [[META45:metadata !.*]], metadata !DIExpression()), [[DBG50]]
+; NOLZCNT-NEXT: br i1 [[X_CURR_ISBITUNSET]], label [[LOOP]], label [[END:%.*]], [[DBG51:!dbg !.*]]
+; NOLZCNT: end:
+; NOLZCNT-NEXT: [[X_CURR_LCSSA:%.*]] = phi i32 [ [[X_CURR]], [[LOOP]] ], [[DBG47]]
+; NOLZCNT-NEXT: ret i32 [[X_CURR_LCSSA]], [[DBG52:!dbg !.*]]
;
entry:
br label %loop
@@ -176,22 +201,47 @@ end:
}
define i32 @p3_constant_mask_15thbit(i32 %x) {
-; ALL-LABEL: @p3_constant_mask_15thbit(
-; ALL-NEXT: entry:
-; ALL-NEXT: br label [[LOOP:%.*]], [[DBG59:!dbg !.*]]
-; ALL: loop:
-; ALL-NEXT: [[X_CURR:%.*]] = phi i32 [ [[X:%.*]], [[ENTRY:%.*]] ], [ [[X_NEXT:%.*]], [[LOOP]] ], [[DBG60:!dbg !.*]]
-; ALL-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR]], [[META55:metadata !.*]], metadata !DIExpression()), [[DBG60]]
-; ALL-NEXT: [[X_CURR_BITMASKED:%.*]] = and i32 [[X_CURR]], 32768, [[DBG61:!dbg !.*]]
-; ALL-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR_BITMASKED]], [[META56:metadata !.*]], metadata !DIExpression()), [[DBG61]]
-; ALL-NEXT: [[X_CURR_ISBITUNSET:%.*]] = icmp eq i32 [[X_CURR_BITMASKED]], 0, [[DBG62:!dbg !.*]]
-; ALL-NEXT: call void @llvm.dbg.value(metadata i1 [[X_CURR_ISBITUNSET]], [[META57:metadata !.*]], metadata !DIExpression()), [[DBG62]]
-; ALL-NEXT: [[X_NEXT]] = shl i32 [[X_CURR]], 1, [[DBG63:!dbg !.*]]
-; ALL-NEXT: call void @llvm.dbg.value(metadata i32 [[X_NEXT]], [[META58:metadata !.*]], metadata !DIExpression()), [[DBG63]]
-; ALL-NEXT: br i1 [[X_CURR_ISBITUNSET]], label [[LOOP]], label [[END:%.*]], [[DBG64:!dbg !.*]]
-; ALL: end:
-; ALL-NEXT: [[X_CURR_LCSSA:%.*]] = phi i32 [ [[X_CURR]], [[LOOP]] ], [[DBG60]]
-; ALL-NEXT: ret i32 [[X_CURR_LCSSA]], [[DBG65:!dbg !.*]]
+; LZCNT-LABEL: @p3_constant_mask_15thbit(
+; LZCNT-NEXT: entry:
+; LZCNT-NEXT: [[X_MASKED:%.*]] = and i32 [[X:%.*]], 65535, [[DBG59:!dbg !.*]]
+; LZCNT-NEXT: [[X_MASKED_NUMLEADINGZEROS:%.*]] = call i32 @llvm.ctlz.i32(i32 [[X_MASKED]], i1 true), [[DBG59]]
+; LZCNT-NEXT: [[X_MASKED_NUMACTIVEBITS:%.*]] = sub i32 32, [[X_MASKED_NUMLEADINGZEROS]], [[DBG59]]
+; LZCNT-NEXT: [[X_MASKED_LEADINGONEPOS:%.*]] = add i32 [[X_MASKED_NUMACTIVEBITS]], -1, [[DBG59]]
+; LZCNT-NEXT: [[LOOP_BACKEDGETAKENCOUNT:%.*]] = sub i32 15, [[X_MASKED_LEADINGONEPOS]], [[DBG59]]
+; LZCNT-NEXT: [[LOOP_TRIPCOUNT:%.*]] = add nuw i32 [[LOOP_BACKEDGETAKENCOUNT]], 1, [[DBG59]]
+; LZCNT-NEXT: [[X_CURR:%.*]] = shl i32 [[X]], [[LOOP_BACKEDGETAKENCOUNT]], [[DBG59]]
+; LZCNT-NEXT: [[X_NEXT:%.*]] = shl i32 [[X]], [[LOOP_TRIPCOUNT]], [[DBG59]]
+; LZCNT-NEXT: br label [[LOOP:%.*]], [[DBG60:!dbg !.*]]
+; LZCNT: loop:
+; LZCNT-NEXT: [[TMP0:%.*]] = phi i32 [ [[X]], [[ENTRY:%.*]] ], [ [[X_NEXT]], [[LOOP]] ], [[DBG59]]
+; LZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR]], [[META55:metadata !.*]], metadata !DIExpression()), [[DBG59]]
+; LZCNT-NEXT: [[X_CURR_BITMASKED:%.*]] = and i32 [[X_CURR]], 32768, [[DBG61:!dbg !.*]]
+; LZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR_BITMASKED]], [[META56:metadata !.*]], metadata !DIExpression()), [[DBG61]]
+; LZCNT-NEXT: [[X_CURR_ISBITUNSET:%.*]] = icmp eq i32 [[X_CURR_BITMASKED]], 0, [[DBG62:!dbg !.*]]
+; LZCNT-NEXT: call void @llvm.dbg.value(metadata i1 [[X_CURR_ISBITUNSET]], [[META57:metadata !.*]], metadata !DIExpression()), [[DBG62]]
+; LZCNT-NEXT: [[TMP1:%.*]] = shl i32 [[X_CURR]], 1, [[DBG63:!dbg !.*]]
+; LZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_NEXT]], [[META58:metadata !.*]], metadata !DIExpression()), [[DBG63]]
+; LZCNT-NEXT: br i1 true, label [[END:%.*]], label [[LOOP]], [[DBG64:!dbg !.*]]
+; LZCNT: end:
+; LZCNT-NEXT: [[X_CURR_LCSSA:%.*]] = phi i32 [ [[X_CURR]], [[LOOP]] ], [[DBG59]]
+; LZCNT-NEXT: ret i32 [[X_CURR_LCSSA]], [[DBG65:!dbg !.*]]
+;
+; NOLZCNT-LABEL: @p3_constant_mask_15thbit(
+; NOLZCNT-NEXT: entry:
+; NOLZCNT-NEXT: br label [[LOOP:%.*]], [[DBG59:!dbg !.*]]
+; NOLZCNT: loop:
+; NOLZCNT-NEXT: [[X_CURR:%.*]] = phi i32 [ [[X:%.*]], [[ENTRY:%.*]] ], [ [[X_NEXT:%.*]], [[LOOP]] ], [[DBG60:!dbg !.*]]
+; NOLZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR]], [[META55:metadata !.*]], metadata !DIExpression()), [[DBG60]]
+; NOLZCNT-NEXT: [[X_CURR_BITMASKED:%.*]] = and i32 [[X_CURR]], 32768, [[DBG61:!dbg !.*]]
+; NOLZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR_BITMASKED]], [[META56:metadata !.*]], metadata !DIExpression()), [[DBG61]]
+; NOLZCNT-NEXT: [[X_CURR_ISBITUNSET:%.*]] = icmp eq i32 [[X_CURR_BITMASKED]], 0, [[DBG62:!dbg !.*]]
+; NOLZCNT-NEXT: call void @llvm.dbg.value(metadata i1 [[X_CURR_ISBITUNSET]], [[META57:metadata !.*]], metadata !DIExpression()), [[DBG62]]
+; NOLZCNT-NEXT: [[X_NEXT]] = shl i32 [[X_CURR]], 1, [[DBG63:!dbg !.*]]
+; NOLZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_NEXT]], [[META58:metadata !.*]], metadata !DIExpression()), [[DBG63]]
+; NOLZCNT-NEXT: br i1 [[X_CURR_ISBITUNSET]], label [[LOOP]], label [[END:%.*]], [[DBG64:!dbg !.*]]
+; NOLZCNT: end:
+; NOLZCNT-NEXT: [[X_CURR_LCSSA:%.*]] = phi i32 [ [[X_CURR]], [[LOOP]] ], [[DBG60]]
+; NOLZCNT-NEXT: ret i32 [[X_CURR_LCSSA]], [[DBG65:!dbg !.*]]
;
entry:
br label %loop
@@ -345,22 +395,46 @@ end:
}
define i32 @p6_constant_mask_signbit_noncanonical(i32 %x) {
-; ALL-LABEL: @p6_constant_mask_signbit_noncanonical(
-; ALL-NEXT: entry:
-; ALL-NEXT: br label [[LOOP:%.*]], [[DBG104:!dbg !.*]]
-; ALL: loop:
-; ALL-NEXT: [[X_CURR:%.*]] = phi i32 [ [[X:%.*]], [[ENTRY:%.*]] ], [ [[X_NEXT:%.*]], [[LOOP]] ], [[DBG105:!dbg !.*]]
-; ALL-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR]], [[META100:metadata !.*]], metadata !DIExpression()), [[DBG105]]
-; ALL-NEXT: [[X_CURR_BITMASKED:%.*]] = and i32 [[X_CURR]], -2147483648, [[DBG106:!dbg !.*]]
-; ALL-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR_BITMASKED]], [[META101:metadata !.*]], metadata !DIExpression()), [[DBG106]]
-; ALL-NEXT: [[X_CURR_ISBITUNSET:%.*]] = icmp eq i32 [[X_CURR_BITMASKED]], 0, [[DBG107:!dbg !.*]]
-; ALL-NEXT: call void @llvm.dbg.value(metadata i1 [[X_CURR_ISBITUNSET]], [[META102:metadata !.*]], metadata !DIExpression()), [[DBG107]]
-; ALL-NEXT: [[X_NEXT]] = shl i32 [[X_CURR]], 1, [[DBG108:!dbg !.*]]
-; ALL-NEXT: call void @llvm.dbg.value(metadata i32 [[X_NEXT]], [[META103:metadata !.*]], metadata !DIExpression()), [[DBG108]]
-; ALL-NEXT: br i1 [[X_CURR_ISBITUNSET]], label [[LOOP]], label [[END:%.*]], [[DBG109:!dbg !.*]]
-; ALL: end:
-; ALL-NEXT: [[X_CURR_LCSSA:%.*]] = phi i32 [ [[X_CURR]], [[LOOP]] ], [[DBG105]]
-; ALL-NEXT: ret i32 [[X_CURR_LCSSA]], [[DBG110:!dbg !.*]]
+; LZCNT-LABEL: @p6_constant_mask_signbit_noncanonical(
+; LZCNT-NEXT: entry:
+; LZCNT-NEXT: [[X_NUMLEADINGZEROS:%.*]] = call i32 @llvm.ctlz.i32(i32 [[X:%.*]], i1 true), [[DBG104:!dbg !.*]]
+; LZCNT-NEXT: [[X_NUMACTIVEBITS:%.*]] = sub i32 32, [[X_NUMLEADINGZEROS]], [[DBG104]]
+; LZCNT-NEXT: [[X_LEADINGONEPOS:%.*]] = add i32 [[X_NUMACTIVEBITS]], -1, [[DBG104]]
+; LZCNT-NEXT: [[LOOP_BACKEDGETAKENCOUNT:%.*]] = sub i32 31, [[X_LEADINGONEPOS]], [[DBG104]]
+; LZCNT-NEXT: [[LOOP_TRIPCOUNT:%.*]] = add nuw i32 [[LOOP_BACKEDGETAKENCOUNT]], 1, [[DBG104]]
+; LZCNT-NEXT: [[X_CURR:%.*]] = shl i32 [[X]], [[LOOP_BACKEDGETAKENCOUNT]], [[DBG104]]
+; LZCNT-NEXT: [[X_NEXT:%.*]] = shl i32 [[X]], [[LOOP_TRIPCOUNT]], [[DBG104]]
+; LZCNT-NEXT: br label [[LOOP:%.*]], [[DBG105:!dbg !.*]]
+; LZCNT: loop:
+; LZCNT-NEXT: [[TMP0:%.*]] = phi i32 [ [[X]], [[ENTRY:%.*]] ], [ [[X_NEXT]], [[LOOP]] ], [[DBG104]]
+; LZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR]], [[META100:metadata !.*]], metadata !DIExpression()), [[DBG104]]
+; LZCNT-NEXT: [[X_CURR_BITMASKED:%.*]] = and i32 [[X_CURR]], -2147483648, [[DBG106:!dbg !.*]]
+; LZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR_BITMASKED]], [[META101:metadata !.*]], metadata !DIExpression()), [[DBG106]]
+; LZCNT-NEXT: [[X_CURR_ISBITUNSET:%.*]] = icmp eq i32 [[X_CURR_BITMASKED]], 0, [[DBG107:!dbg !.*]]
+; LZCNT-NEXT: call void @llvm.dbg.value(metadata i1 [[X_CURR_ISBITUNSET]], [[META102:metadata !.*]], metadata !DIExpression()), [[DBG107]]
+; LZCNT-NEXT: [[TMP1:%.*]] = shl i32 [[X_CURR]], 1, [[DBG108:!dbg !.*]]
+; LZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_NEXT]], [[META103:metadata !.*]], metadata !DIExpression()), [[DBG108]]
+; LZCNT-NEXT: br i1 true, label [[END:%.*]], label [[LOOP]], [[DBG109:!dbg !.*]]
+; LZCNT: end:
+; LZCNT-NEXT: [[X_CURR_LCSSA:%.*]] = phi i32 [ [[X_CURR]], [[LOOP]] ], [[DBG104]]
+; LZCNT-NEXT: ret i32 [[X_CURR_LCSSA]], [[DBG110:!dbg !.*]]
+;
+; NOLZCNT-LABEL: @p6_constant_mask_signbit_noncanonical(
+; NOLZCNT-NEXT: entry:
+; NOLZCNT-NEXT: br label [[LOOP:%.*]], [[DBG104:!dbg !.*]]
+; NOLZCNT: loop:
+; NOLZCNT-NEXT: [[X_CURR:%.*]] = phi i32 [ [[X:%.*]], [[ENTRY:%.*]] ], [ [[X_NEXT:%.*]], [[LOOP]] ], [[DBG105:!dbg !.*]]
+; NOLZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR]], [[META100:metadata !.*]], metadata !DIExpression()), [[DBG105]]
+; NOLZCNT-NEXT: [[X_CURR_BITMASKED:%.*]] = and i32 [[X_CURR]], -2147483648, [[DBG106:!dbg !.*]]
+; NOLZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_CURR_BITMASKED]], [[META101:metadata !.*]], metadata !DIExpression()), [[DBG106]]
+; NOLZCNT-NEXT: [[X_CURR_ISBITUNSET:%.*]] = icmp eq i32 [[X_CURR_BITMASKED]], 0, [[DBG107:!dbg !.*]]
+; NOLZCNT-NEXT: call void @llvm.dbg.value(metadata i1 [[X_CURR_ISBITUNSET]], [[META102:metadata !.*]], metadata !DIExpression()), [[DBG107]]
+; NOLZCNT-NEXT: [[X_NEXT]] = shl i32 [[X_CURR]], 1, [[DBG108:!dbg !.*]]
+; NOLZCNT-NEXT: call void @llvm.dbg.value(metadata i32 [[X_NEXT]], [[META103:metadata !.*]], metadata !DIExpression()), [[DBG108]]
+; NOLZCNT-NEXT: br i1 [[X_CURR_ISBITUNSET]], label [[LOOP]], label [[END:%.*]], [[DBG109:!dbg !.*]]
+; NOLZCNT: end:
+; NOLZCNT-NEXT: [[X_CURR_LCSSA:%.*]] = phi i32 [ [[X_CURR]], [[LOOP]] ], [[DBG105]]
+; NOLZCNT-NEXT: ret i32 [[X_CURR_LCSSA]], [[DBG110:!dbg !.*]]
;
entry:
br label %loop
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