JIT: ensure AVX512 ternary operands aren't used twice (#91851)

AndyAyersMS · web-flow · commit c84ccfa5d1b6 · 2023-09-11T07:24:57.000-07:00
Don't spill unused zeros early; we might decide to use them later. Fixes #91796.
diff --git a/src/coreclr/jit/hwintrinsicxarch.cpp b/src/coreclr/jit/hwintrinsicxarch.cpp
@@ -3602,17 +3602,19 @@ GenTree* Compiler::impSpecialIntrinsic(NamedIntrinsic        intrinsic,
                     op2 = impSIMDPopStack();
                     op1 = impSIMDPopStack();
 
-                    if (unusedVal1)
+                    // Consume operands we won't use, in case they have side effects.
+                    //
+                    if (unusedVal1 && !(*val1)->IsVectorZero())
                     {
                         impAppendTree(gtUnusedValNode(*val1), CHECK_SPILL_ALL, impCurStmtDI);
                     }
 
-                    if (unusedVal2)
+                    if (unusedVal2 && !(*val2)->IsVectorZero())
                     {
                         impAppendTree(gtUnusedValNode(*val2), CHECK_SPILL_ALL, impCurStmtDI);
                     }
 
-                    if (unusedVal3)
+                    if (unusedVal3 && !(*val3)->IsVectorZero())
                     {
                         impAppendTree(gtUnusedValNode(*val3), CHECK_SPILL_ALL, impCurStmtDI);
                     }

Original file line number	Diff line number	Diff line change
`@@ -3602,17 +3602,19 @@ GenTree* Compiler::impSpecialIntrinsic(NamedIntrinsic intrinsic,`
`3602`	`3602`	`op2 = impSIMDPopStack();`
`3603`	`3603`	`op1 = impSIMDPopStack();`
`3604`	`3604`
`3605`		`- if (unusedVal1)`
	`3605`	`+ // Consume operands we won't use, in case they have side effects.`
	`3606`	`+ //`
	`3607`	`+ if (unusedVal1 && !(*val1)->IsVectorZero())`
`3606`	`3608`	`{`
`3607`	`3609`	`impAppendTree(gtUnusedValNode(*val1), CHECK_SPILL_ALL, impCurStmtDI);`
`3608`	`3610`	`}`
`3609`	`3611`
`3610`		`- if (unusedVal2)`
	`3612`	`+ if (unusedVal2 && !(*val2)->IsVectorZero())`
`3611`	`3613`	`{`
`3612`	`3614`	`impAppendTree(gtUnusedValNode(*val2), CHECK_SPILL_ALL, impCurStmtDI);`
`3613`	`3615`	`}`
`3614`	`3616`
`3615`		`- if (unusedVal3)`
	`3617`	`+ if (unusedVal3 && !(*val3)->IsVectorZero())`
`3616`	`3618`	`{`
`3617`	`3619`	`impAppendTree(gtUnusedValNode(*val3), CHECK_SPILL_ALL, impCurStmtDI);`
`3618`	`3620`	`}`