[llvm-commits] [llvm] r57039 - in /llvm/trunk: lib/CodeGen/RegAllocLocal.cpp test/CodeGen/X86/local-liveness.ll

[Dan Gohman]

Author: djg
Date: Fri Oct  3 19:31:14 2008
New Revision: 57039

URL: http://llvm.org/viewvc/llvm-project?rev=57039&view=rev
Log:
Fix a bug in the local allocator's liveness computation where it
was setting kill flags on tied uses in two-address instructions.
The kill flags were causing the allocator to think it could
allocate the use and its tied def in different registers.

Added:
    llvm/trunk/test/CodeGen/X86/local-liveness.ll
Modified:
    llvm/trunk/lib/CodeGen/RegAllocLocal.cpp

Modified: llvm/trunk/lib/CodeGen/RegAllocLocal.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegAllocLocal.cpp?rev=57039&r1=57038&r2=57039&view=diff

==============================================================================
--- llvm/trunk/lib/CodeGen/RegAllocLocal.cpp (original)
+++ llvm/trunk/lib/CodeGen/RegAllocLocal.cpp Fri Oct  3 19:31:14 2008
@@ -651,9 +651,11 @@
     // Physical registers and those that are not live-out of the block
     // are killed/dead at their last use/def within this block.
     if (isPhysReg || !usedOutsideBlock) {
-      if (MO.isUse())
-        MO.setIsKill(true);
-      else
+      if (MO.isUse()) {
+        // Don't mark uses that are tied to defs as kills.
+        if (MI->getDesc().getOperandConstraint(idx, TOI::TIED_TO) == -1)
+          MO.setIsKill(true);
+      } else
         MO.setIsDead(true);
     }
   }

Added: llvm/trunk/test/CodeGen/X86/local-liveness.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/local-liveness.ll?rev=57039&view=auto

==============================================================================
--- llvm/trunk/test/CodeGen/X86/local-liveness.ll (added)
+++ llvm/trunk/test/CodeGen/X86/local-liveness.ll Fri Oct  3 19:31:14 2008
@@ -0,0 +1,31 @@
+; RUN: llvm-as < %s | llc -march=x86 -regalloc=local | grep {subl	%eax, %esi}
+
+; Local regalloc shouldn't assume that both the uses of the
+; sub instruction are kills, because one of them is tied
+; to an output. Previously, it was allocating both inputs
+; in the same register.
+
+define i32 @func_3() nounwind {
+entry:
+	%retval = alloca i32		; <i32*> [#uses=2]
+	%g_323 = alloca i8		; <i8*> [#uses=2]
+	%p_5 = alloca i64, align 8		; <i64*> [#uses=2]
+	%0 = alloca i32		; <i32*> [#uses=2]
+	%"alloca point" = bitcast i32 0 to i32		; <i32> [#uses=0]
+	store i64 0, i64* %p_5, align 8
+	store i8 1, i8* %g_323, align 1
+	%1 = load i8* %g_323, align 1		; <i8> [#uses=1]
+	%2 = sext i8 %1 to i64		; <i64> [#uses=1]
+	%3 = load i64* %p_5, align 8		; <i64> [#uses=1]
+	%4 = sub i64 %3, %2		; <i64> [#uses=1]
+	%5 = icmp sge i64 %4, 0		; <i1> [#uses=1]
+	%6 = zext i1 %5 to i32		; <i32> [#uses=1]
+	store i32 %6, i32* %0, align 4
+	%7 = load i32* %0, align 4		; <i32> [#uses=1]
+	store i32 %7, i32* %retval, align 4
+	br label %return
+
+return:		; preds = %entry
+	%retval1 = load i32* %retval		; <i32> [#uses=1]
+	ret i32 %retval1
+}