[GlobalIsel][X86] Legalize G_BSWAP II

[tschuett]

Summary

Note the workaround for 32 bit

[arsenm]

llvm/test/CodeGen/X86/GlobalISel/legalize-bswap.mir

76 ↗

(On Diff #527016)

Needs some non-power-of-2 tests

[tschuett]

add s17

[arsenm]

llvm/test/CodeGen/X86/GlobalISel/legalize-bswap.mir

9 ↗

(On Diff #527492)

I think something went wrong with the latest diff.

Anyway, you need a non-power-of-2 test in-between the clamped range. That's the case which wouldn't be caught if you dropped the widenScalarToNextPow2 part

[tschuett]

fix I

[tschuett]

second attempt

[RKSimon]

llvm/lib/Target/X86/X86LegalizerInfo.cpp

105

Add the sMax variable from D151878 instead of s64

127

If you're going to use legalIf, why not merge them (the plan is to get rid of the if (Subtarget.is64Bit()) if-else entirely):

return Query.Types[0] == s32 || (Subtarget.is64Bit() && Query.Types[0] == s64);

[tschuett]

superseded by https://reviews.llvm.org/D151915

llvm/lib/Target/X86/X86LegalizerInfo.cpp

LegacyInfo.setLegalizeScalarToDifferentSizeStrategy(
       LegacyLegalizerInfo::widenToLargerTypesUnsupportedOtherwise);
   LegacyInfo.setLegalizeScalarToDifferentSizeStrategy(
       G_CONSTANT, 0,
       LegacyLegalizerInfo::widenToLargerTypesAndNarrowToLargest);
 
   getActionDefinitionsBuilder({G_MEMCPY, G_MEMMOVE, G_MEMSET}).libcall();
 
 
+  if (Subtarget.is64Bit()) {
+    getActionDefinitionsBuilder(G_BSWAP)
+      .legalFor({s32, s64})
+      .widenScalarToNextPow2(0, /*Min=*/32)
+      .clampScalar(0, s32, s64);
+
+    if (Subtarget.hasPOPCNT()) {
+      // popcount (POPCNT)
+      getActionDefinitionsBuilder(G_CTPOP)
+        .legalFor({{s16, s16}, {s32, s32}, {s64, s64}})
+        .widenScalarToNextPow2(1, /*Min=*/16)
+        .clampScalar(1, s16, s64);
+    }
+
+    if (Subtarget.hasLZCNT()) {
+      // count leading zeros (LZCNT)
+      getActionDefinitionsBuilder(G_CTLZ)
+        .legalFor({{s16, s16}, {s32, s32}, {s64, s64}})
+        .widenScalarToNextPow2(1, /*Min=*/16)
+        .clampScalar(1, s16, s64);
+    }
+  } else { // 32-bit
+    getActionDefinitionsBuilder(G_BSWAP)
+      .legalIf([=](const LegalityQuery &Query) {
+        // workaround for legalFor
+        return Query.Types[0] == s32;
+      })
+      .widenScalarToNextPow2(0, /*Min=*/32)
+      .clampScalar(0, s32, s32);
+
+    if (Subtarget.hasPOPCNT()) {
+      // popcount
+      getActionDefinitionsBuilder(G_CTPOP)
+        .legalFor({{s16, s16}, {s32, s32}})
+        .widenScalarToNextPow2(1, /*Min=*/16)
+        .clampScalar(1, s16, s32);
+    }
+
+    if (Subtarget.hasLZCNT()) {
+      // count leading zeros (LZCNT)
+      getActionDefinitionsBuilder(G_CTLZ)
+        .legalFor({{s16, s16}, {s32, s32}})
+        .widenScalarToNextPow2(1, /*Min=*/16)
+        .clampScalar(1, s16, s32);
+    }
+  }
+
   LegacyInfo.computeTables();
   verify(*STI.getInstrInfo());
 }
 
 bool X86LegalizerInfo::legalizeIntrinsic(LegalizerHelper &Helper,
                                          MachineInstr &MI) const {
   return true;
 }