Merge pull request #863 from jbj/ir-variableLiveOnEntryToBlock-rhs

dave-bartolomeo · web-flow · commit aadd5cf2023f · 2019-02-04T10:47:29.000-08:00
C++: Speed up variableLiveOnEntryToBlock in IR
diff --git a/cpp/ql/src/semmle/code/cpp/ir/implementation/aliased_ssa/internal/SSAConstruction.qll b/cpp/ql/src/semmle/code/cpp/ir/implementation/aliased_ssa/internal/SSAConstruction.qll
@@ -352,7 +352,7 @@ cached private module Cached {
   }
 
   private predicate ssa_variableUpdate(Alias::VirtualVariable vvar,
-      OldInstruction instr, OldBlock block, int index) {
+      OldBlock block, int index, OldInstruction instr) {
     block.getInstruction(index) = instr and
     Alias::getResultMemoryAccess(instr).getVirtualVariable() = vvar
   }
@@ -370,11 +370,11 @@ cached private module Cached {
   }
 
   private predicate defUseRank(Alias::VirtualVariable vvar, OldBlock block, int rankIndex, int index) {
-    index = rank[rankIndex](int j | hasDefinition(vvar, block, j) or hasUse(vvar, _, block, j))
+    index = rank[rankIndex](int j | hasDefinition(vvar, block, j) or hasUse(vvar, block, j, _))
   }
 
-  private predicate hasUse(Alias::VirtualVariable vvar, OldInstruction use, OldBlock block,
-      int index) {
+  private predicate hasUse(Alias::VirtualVariable vvar, OldBlock block, int index,
+      OldInstruction use) {
     exists(Alias::MemoryAccess access |
       (
         access = Alias::getOperandMemoryAccess(use.getAnOperand())
@@ -392,10 +392,16 @@ cached private module Cached {
   }
 
   private predicate variableLiveOnEntryToBlock(Alias::VirtualVariable vvar, OldBlock block) {
-    exists (int index | hasUse(vvar, _, block, index) |
-      not exists (int j | ssa_variableUpdate(vvar, _, block, j) | j < index)
-    ) or
-    (variableLiveOnExitFromBlock(vvar, block) and not ssa_variableUpdate(vvar, _, block, _))
+    exists(int firstAccess |
+      hasUse(vvar, block, firstAccess, _) and
+      firstAccess = min(int index |
+          hasUse(vvar, block, index, _)
+          or
+          ssa_variableUpdate(vvar, block, index, _)
+        )
+    )
+    or
+    (variableLiveOnExitFromBlock(vvar, block) and not ssa_variableUpdate(vvar, block, _, _))
   }
 
   pragma[noinline]
@@ -422,7 +428,7 @@ cached private module Cached {
   private predicate hasUseAtRank(Alias::VirtualVariable vvar, OldBlock block, int rankIndex,
       OldInstruction use) {
     exists(int index |
-      hasUse(vvar, use, block, index) and
+      hasUse(vvar, block, index, use) and
       defUseRank(vvar, block, rankIndex, index)
     )
   }
diff --git a/cpp/ql/src/semmle/code/cpp/ir/implementation/unaliased_ssa/internal/SSAConstruction.qll b/cpp/ql/src/semmle/code/cpp/ir/implementation/unaliased_ssa/internal/SSAConstruction.qll
@@ -352,7 +352,7 @@ cached private module Cached {
   }
 
   private predicate ssa_variableUpdate(Alias::VirtualVariable vvar,
-      OldInstruction instr, OldBlock block, int index) {
+      OldBlock block, int index, OldInstruction instr) {
     block.getInstruction(index) = instr and
     Alias::getResultMemoryAccess(instr).getVirtualVariable() = vvar
   }
@@ -370,11 +370,11 @@ cached private module Cached {
   }
 
   private predicate defUseRank(Alias::VirtualVariable vvar, OldBlock block, int rankIndex, int index) {
-    index = rank[rankIndex](int j | hasDefinition(vvar, block, j) or hasUse(vvar, _, block, j))
+    index = rank[rankIndex](int j | hasDefinition(vvar, block, j) or hasUse(vvar, block, j, _))
   }
 
-  private predicate hasUse(Alias::VirtualVariable vvar, OldInstruction use, OldBlock block,
-      int index) {
+  private predicate hasUse(Alias::VirtualVariable vvar, OldBlock block, int index,
+      OldInstruction use) {
     exists(Alias::MemoryAccess access |
       (
         access = Alias::getOperandMemoryAccess(use.getAnOperand())
@@ -392,10 +392,16 @@ cached private module Cached {
   }
 
   private predicate variableLiveOnEntryToBlock(Alias::VirtualVariable vvar, OldBlock block) {
-    exists (int index | hasUse(vvar, _, block, index) |
-      not exists (int j | ssa_variableUpdate(vvar, _, block, j) | j < index)
-    ) or
-    (variableLiveOnExitFromBlock(vvar, block) and not ssa_variableUpdate(vvar, _, block, _))
+    exists(int firstAccess |
+      hasUse(vvar, block, firstAccess, _) and
+      firstAccess = min(int index |
+          hasUse(vvar, block, index, _)
+          or
+          ssa_variableUpdate(vvar, block, index, _)
+        )
+    )
+    or
+    (variableLiveOnExitFromBlock(vvar, block) and not ssa_variableUpdate(vvar, block, _, _))
   }
 
   pragma[noinline]
@@ -422,7 +428,7 @@ cached private module Cached {
   private predicate hasUseAtRank(Alias::VirtualVariable vvar, OldBlock block, int rankIndex,
       OldInstruction use) {
     exists(int index |
-      hasUse(vvar, use, block, index) and
+      hasUse(vvar, block, index, use) and
       defUseRank(vvar, block, rankIndex, index)
     )
   }

Original file line number	Diff line number	Diff line change
`@@ -352,7 +352,7 @@ cached private module Cached {`
`352`	`352`	`}`
`353`	`353`
`354`	`354`	`private predicate ssa_variableUpdate(Alias::VirtualVariable vvar,`
`355`		`- OldInstruction instr, OldBlock block, int index) {`
	`355`	`+ OldBlock block, int index, OldInstruction instr) {`
`356`	`356`	`block.getInstruction(index) = instr and`
`357`	`357`	`Alias::getResultMemoryAccess(instr).getVirtualVariable() = vvar`
`358`	`358`	`}`
`@@ -370,11 +370,11 @@ cached private module Cached {`
`370`	`370`	`}`
`371`	`371`
`372`	`372`	`private predicate defUseRank(Alias::VirtualVariable vvar, OldBlock block, int rankIndex, int index) {`
`373`		`- index = rank[rankIndex](int j \| hasDefinition(vvar, block, j) or hasUse(vvar, _, block, j))`
	`373`	`+ index = rank[rankIndex](int j \| hasDefinition(vvar, block, j) or hasUse(vvar, block, j, _))`
`374`	`374`	`}`
`375`	`375`
`376`		`- private predicate hasUse(Alias::VirtualVariable vvar, OldInstruction use, OldBlock block,`
`377`		`- int index) {`
	`376`	`+ private predicate hasUse(Alias::VirtualVariable vvar, OldBlock block, int index,`
	`377`	`+ OldInstruction use) {`
`378`	`378`	`exists(Alias::MemoryAccess access \|`
`379`	`379`	`(`
`380`	`380`	`access = Alias::getOperandMemoryAccess(use.getAnOperand())`
`@@ -392,10 +392,16 @@ cached private module Cached {`
`392`	`392`	`}`
`393`	`393`
`394`	`394`	`private predicate variableLiveOnEntryToBlock(Alias::VirtualVariable vvar, OldBlock block) {`
`395`		`- exists (int index \| hasUse(vvar, _, block, index) \|`
`396`		`- not exists (int j \| ssa_variableUpdate(vvar, _, block, j) \| j < index)`
`397`		`- ) or`
`398`		`- (variableLiveOnExitFromBlock(vvar, block) and not ssa_variableUpdate(vvar, _, block, _))`
	`395`	`+ exists(int firstAccess \|`
	`396`	`+ hasUse(vvar, block, firstAccess, _) and`
	`397`	`+ firstAccess = min(int index \|`
	`398`	`+ hasUse(vvar, block, index, _)`
	`399`	`+ or`
	`400`	`+ ssa_variableUpdate(vvar, block, index, _)`
	`401`	`+ )`
	`402`	`+ )`
	`403`	`+ or`
	`404`	`+ (variableLiveOnExitFromBlock(vvar, block) and not ssa_variableUpdate(vvar, block, _, _))`
`399`	`405`	`}`
`400`	`406`
`401`	`407`	`pragma[noinline]`
`@@ -422,7 +428,7 @@ cached private module Cached {`
`422`	`428`	`private predicate hasUseAtRank(Alias::VirtualVariable vvar, OldBlock block, int rankIndex,`
`423`	`429`	`OldInstruction use) {`
`424`	`430`	`exists(int index \|`
`425`		`- hasUse(vvar, use, block, index) and`
	`431`	`+ hasUse(vvar, block, index, use) and`
`426`	`432`	`defUseRank(vvar, block, rankIndex, index)`
`427`	`433`	`)`
`428`	`434`	`}`